Unit 3 Reflection

This unit in physics I learned about...

Newton’s 3rd Law:
When began our unit by learning about Newton's second law which states that:

For every action there is an equal and opposite reaction

We did a lab where a large truck and a small civic collide and we used Newtons second law, a=fnet/m, to find the force on each of the cars to prove Newton's 3rd law. We found out that the acceleration of the small car was 1.61 m/s^2, and its mass was .488 kg. We then found the large car's acceleration of 1.85, and mass of .991. We used Newton's 2nd law to solve, the small car: 1.61*.488= .861N. We did the same for the large car: 1.85 *.991= .997. The forces are so similar, and in a situation where we have more exact results, the forces would be exact, therefore proving Newton's 3rd law.

Action/Reaction Pairs:
With action and reaction pairs, there are 3 rules:
--> subject stays the same
--> verb is the same
--> directions switch
the example of an apple sitting on a table has an action/reaction pair: 
the apple pulls the earth up
the earth pulls the apple down
the verbs and the subject both stay the same, while the direction switches.

In the horse and buggy problem, the reason the cart moves is because of action/reaction pairs:

1. horse pulls buggy forward
buggy pulls horse backward
2. horse pushes ground backward
ground pushes horse forward
3. buggy pushes ground forward
ground pushes buggy forward

The horse pulls the buggy with an equal force that the buggy pulls back with. We know this because of Newton's 3rd law which states that with every action there is an equal and opposite reaction.
The horse and cart move forward in the horses direction because the horse pushes the ground harder then the buggy pushes the ground.

When a train runs into a parked car, both will exert the same force because of Newton's 3rd law: every action has an equal and opposite reaction. When we think about which one will have the greater acceleration though, it changes. The smaller car has the greater acceleration because the mass is smaller, and the force needs to be equal to the larger, so the mass is small and the acceleration is large, as shown below.

F = Am vs F=AM

Forces in perpendicular directions:

Why does the block slide down the ramp? When solving this problem. begin with drawing in the total gravity (the box being pulled down by the earth) and the total support (both in blue). Then connect them (in green), and draw a diagonal (in orange) and this is the total force on the system, thus the direction the box with slide down. If we were to plug in 100N for both fsupport and fgravity, the Pythagorean theorem equation (a^2 + b^2 = c^2) would be used and result in:

100^2 + 100^2 = c^2

10,000 + 10,000 = c^2

20,000 = c^2

c = 141N

This example is a lot like the example of which side of the rope will be more likely to break, shown below. The first step is to show that the ball has force acting on it and draw in the fweight going down and the fsupport going up. Using this fsupport arrow, draw two parallel lines to the ropes both intersecting at the top of the arrow. Where the line drawn intersects the rope, draw a line from that to the ball on both sides. This represents the ftension. The side with the longest line is the side that will break because it has more tension on it.

Gravity and Tides:

Everything with a mass attracts all other things with mass. Meaning that even out beyond the earth, the universe is being pulled together by its attraction towards each other. Force depends on the mass of an object (f~m) and the distance between the objects (f~1/d). When a person is standing on the top of a mountain, the force will be less compared to sea level becasue the distance is greater from the surface on the mountain, and therefore the force and the weight will be less as well.

The Universal Gravitational Formula:

F = G m1m2

d^2

A person is standing on the face of the earth and we are trying to find the gravity, and in order to do this, we can use the universal gravitational formula and simply plug things in. The G will always be 6.67x10^-11, and is this case, lets say that the mass of the person will be 600N or 6.0x10^1. The mass of the earth = 5.98x11^24kg. And finally the distance = 6.37x10^6m (radius of earth). To begin, you plug everything in, not forgetting that in the denominator, both the 6.37 and the 6 from 10^6 is squared. From here, to make it easier, separate the exponents, making the decimals in one group and the scientific notation numbers in another. In the first group multiply all the numbers on top and then divide by the numerator that has been squared. For the scientific notation numbers, simply add the exponents in the numerator, and square the exponent in the denominator, and then subtract as shown off to the right side of the image. From here, there is a decimal

multiplied by a number with an exponent: 5.90 x 100 is 590N which is compared to 600 N (the person). To find the acceleration, plug in the numbers to a = fnet

m

590/60 = 9.8m/s^2 pulled to the earth

GRAVITY!!

The reasons for tides is all connected to the moon and sun and the force between them. As the sun is significantly larger than the moon and, the moon still causes the tides because of the difference in force is greater from the moon. If the moon on side A of the earth has a force of 15, and a force of 5 on side B, and then sun has a force on earth of 20 on side A and 18 on side B, then the reason that tides is causes by the moon and not the sun is becsue of the difference: 20-18=2, while 15-5=10N. The reason that lakes don't experience tides is because it is not large enough and doesn't have a body of water on the opposite side to effect it and pull towards the moon.

Momentum, and Impulse momentum relationship:

We begin with knowing that:

P = momentum

J = Impulse

We know that momentum = mass x velocity (P=mv)

change in P = Pfinal - Pinitial

The change in P is going to be the same no matter how you stop it, and that is why the impulse = force x time force is applied. J = change in P

So why do airbags keep is safe?

p = mv When someone gets in a car accident, the car is going from moving to not moving

no matter how they are stopped

Δp=  Therefore the change in momentum is the same regardless of how the car is stopped

pfinal-pinitial

ΔP = J Since the change in momentum (P) is the same no matter how the car stops, the

impulse (J) is also the same

J= FΔt The car with airbags will stop over a period of time. This causes the force on the 

J= F Δt person to be same, A small force means less danger so the person will be safer

This explanation can be used for why climbers use nylon rope, why gymnast use bouncy mats or even how to win an egg toss challenge.

We can use these equations to help us solve the problem of: a car with a mass of 100kg starts at a speed of 50m/s and comes to a stop.

Δp = pfinal-pinitial

p = mv

Δmv = mvfinal - mvinitial 

(1000)(0) - (1000)(50)

0 -50000 kgm/s

Δp = -50000 kgm/s

J = 50000 Ns

The reason that bullet proof vests are safe is becasue the bullets stick instead of bounce off. Vests that have bullets bounce off taek 2 forces:when the bullet hits, that is one force, and this is what vests that stick do, but a bullet that bounces must now bounce off creating another force.

Conservation of Momentum:

We know that forces are equal and opposite because of Newton's 3rd law. So if 2 carts collide, one (cart a) being 2kg and going 10m/s to the right, and the other (cart b) weighing 5kg and not moving with a velocity of 0m/s, we can solve to find the velocity of carb b since it will go and cart a will stop. As seen to the left, you simply plug in the numbers and into the equation and solve. This equation is meant for when the 2 objects don't stick together, but for when 2 objects do stick together, the equation is different:

MaVa + MbVb = Ma + b (Vab)

*Something to remember is that when 2 objects are going in opposite directions, one will be positive and the other will be negative. 

When 2 objects hit each other, and go off into different directions, to the right is what happens. The momentum is conserved, having the same x and y in the before and after. it is a simple 3,4,5 triangle and results in the 2 sides adding up to become equal in the end.

Overview of the Lab:

In our lab Cart A (2kg) rolled into Cart B (1kg) that was at rest. The carts stuck together, and with gathered data, we can confirm the Law of Conservation of Momentum.

First, write the equation of the line --> y = 2.933x

Second, fill in the equation with what is on the x and y axis --> ptotal before = 2.33x

Third, ptotal before = ptotal after which is ptotal before = (Ma +b)(Vab) is the equation used

Forth, Figure out part of the equation that represents slope --> Ma + b, 2 +1 =3 compared to 2.933

Fifth, compare the theatrical slope to the actual slope and a close number confirms --> 3 compared to 2.933 = confirmed

In this unit I found that understanding tides and gravity was very difficult for me. I was able to understand them a little better by help from my peers, and watching the video's Mrs. Lawrence made for us. I still have trouble with them because the idea is so large for me to wrap my mind around. I think that this unit I was bale to keep up well, but I still struggled with managing my time and really fully studying for my quizzes. I did my homework, and turned in my blog posts on time. I think this unit I performed weaker than the previous units. I think something I can improve is my persistence, because I think that if I am more persistence in class I will be able to help myself understand the problems and thus help me to understand the unit better. For my unit podcast, I think my group was able to get it done, but we struggled with all working together. My goals for next unit is to get all my homework done on time. I think that if I am able to get my homework in on time, I will be able to study better, and it will help me at the moment.

Tides are cool

 In this video, by Paul Hewitt, the author of our physics text book, does a great job explaining the tides and how the gravitational pull between the earth and the moon have to do with each other. Hewitt talks about how the force between earth and the moon causes the ocean to be pulled towards the moon. When the earth rotates, taking a total of 24 hours to do so, there is a high tide twice (every 6 hours) and a low tide also twice (every 6 hours). The high tide occurs when that side of the earth is facing towards the moon, causing the force to pull the ocean towards it, and this happens on the opposite side of the earth as well because of the negative pull. This causes the shape to be an oval with the earth in the middle rotating.

Unit 2 Reflection

In this unit, we learned about...

Newtons 2nd Law:
During our 2nd unit we learned first about Newton's Second Law which states...

a = fnet            or            acceleration = total force
        m                                                        mass
This equation in mathematical terms is that acceleration is directly proportional to force and inversely proportional to mass. Meaning, that if acceleration increases, the force will also increase and the mass will decrease.
a ~ f     and     a ~ 1
                            m

I the example to the right, the 10kg box is being pushed with 20N of force to the right. to find the acceleration, we simply plug in 20N for force and 10kg for mass and solve to get 2 m/s^2. In the example to the left, the 10kg box is being pushed downward with a force of 10N. We know that the force is 10N because whenever an object is falling down, the only force acting upon it will be gravity which is always 10. So we plug the 10kg and 10N of gravity into the weight = mass x gravity and find that the weight (the force) is 100N. We then take this and plug it into the acceleration equation to find that the acceleration will be 10 m/s^2.

Newtons 2nd Law Lab:
We did a lab involving Newtons 2nd law to find how the acceleration of a system is related to the mass and the force on a system...
In experiment A, we set up the lab so that the force was being kept constant (the hanging weight), buy we added mass to the system each round. On the first round, we didn't add anything to the cart, and the acceleration was fast. For the 2nd round, we added 10 grams of weight to the cart, and continued to after each round. As we added more weight, we noticed a trend: the acceleration was decreasing. We related this back to Newtons 2nd law where the acceleration is inversely proportional to mass. In this case the acceleration was decreasing because the mass was increasing, thus, proving Newtons 2nd law to be true.
In experiment B, we did something different in the sense that the mass was kept constant throughout this entire experiment, but we increased the force. We started out with all the weight in the cart, and for each round we removed a 10kg weight from the cart and moved it over to the force (the hanging weight). In this experiment, as the force of the cart increased, the acceleration  increased, thus, proving again that Newtons 2nd law saying that acceleration is proportional to force, is true because they both increased in this example.
Newtons 2nd law can also be written where a = fnet x 1/m. So for experiment A, we kept the force constant, and since we know that whatever is being kept constant is the slope on a graph, we can compare the two:

                                                       a =         fnet          x 1/m 

                                                       y =      m (slope)    x X

But in experiment B, we kept the mass of the system constant, so in this case, the mass was being compared tot he slope:

                                                       a =         1/m          x fnet
                                                       y =      m (slope)    x X

Falling Through the Air:
We continued to learn about Newtons 2nd law, but now we were learning about how it was involved with skydiving.
While skydiving, we learned that when you first jump out of the plane, your velocity will be 0 m/s. Lets say that your fweight is 100N, the total air resistance, or fair, is going to be 100-0 which is 0N. The acceleration when you first jump out let say is 10 m/s^2. Once you start moving, lets say that your fair is now 80N. This will mean that the total force will be 100-80 which is 20N. Once you finally reach terminal velocity which is just traveling at a constant speed, your fair will equal your fweight, therefore, in this case, it will be 100-100 = 0N (terminal velocity A). This is the time where you open your parachute so that you can fall slower. Once the parachute is opened your fnet will now be in the opposite direction, meaning that the acceleration is upward, but the velocity is downward. Once the fair goes back down and reaches the same as the fweight, the fnet will be 0N, therefore you are at your second terminal velocity. The only difference between terminal velocity A and B is that B is slower, there fnet, and fair are the same. Two things that increase the force of air resistance are speed and surface area.
Connecting it back to Newtons 2nd law, we learned that the acceleration is going to decrease as an object falls thought the air until it reaches terminal velocity adn stays at that speed. Because fo Newtons 2nd law we know that acceleration dn net force are directly proportional, therefore since acceleration is decreasing, we know that fnet is also decreaseing.
We can change the situation to a lead ball and a ping pong ball and find out which one hits the ground first as well. When the lead ball and the ping pong ball are dropped from a short hight, they will land at the same time because they didn't have much time to really start speeding up. But when the two balls are dropped from a higher hight, the lead ball will land first because it needs a greater fair to reach its terminal velocity.

Free Fall- Falling Straight Down:
When objects are falling in free fall, it means that the only force acting on it is gravity, there is no air force. When an object is dropped straight down, at 0 seconds, it will have a velocity of 0m/s. It is important to remember that even when the object is first dropped, the acceleration will always be 10m/s^2. At 1 second, the velocity will have increased by 10 m/s, therefore at 1 sec, the velocity is 10m/s. At 2 seconds, the velocity will be 30m/s and so on. To find the distance that this ball has been dropped, the equation d = 1/2gt^2. So to find how far the ball has dropped at 2 seconds, we plug in
d = 1/2 (10)(2)^2, which when solved comes out to be 20 m. To find the velocity the ball was going at 2 seconds, you use the equation v = gt, which is v = (10)((2), and it equals 20 m/s.
When an object falls straight down, the equations used are:

how far --> d = 1/2gt^2               and                 how fast --> v = gt

Free Fall- Throwing things straight up:

When working with free falling objects that are thrown straight up into the air, the most helpful thing to do is draw a picture. When an object is thrown straight up, it will always start at the initial speed and as it gets higher, it will lose its speed. 

Lets say a ball is thrown up with an initial velocity of 40m/s. At 0 seconds, the ball will be traveling at 40m/s. The acceleration will also always be 10m/s^2. In the example picture to the right, the ball is thrown up with initial velocity 40m/s, and you can also see at which point the ball is at what time. 

Looking at the example picture, it takes 4 seconds for the ball to get to the top of its path. It is in the air for 8 seconds. The velocity at the top of the path is 0m/s. The acceleration at the top of the path is 10m/s^2. The velocity after 6 seconds is going to be 20m/s. I was just able to find all those answers from drawing a picture, thus: draw a picture, it makes life easier. 

In order to find how high the ball is at the top of its path, you use the d = 1/2gt^2:

d = 1/2gt^2

d = 1/2 (10)(4)^2

d = 80m

After 6 seconds, how high is the ball:

  total it fell                                                        d = 1/2(10)(2)^2                      80

- distance it fell to reach the point        -->         d = 20                       -->        - 20

  hight at 6 sec                                                                                                   60m

Free Fall- Falling at an Angle:

In the example picture to the right, the person is moving 10m/s in the horizontal direction and 0m/s in the vertical direction at 0 sec. As the person jumps, the horizontal direction doesn't change, but the vertical direction does, speeding up 10m/s^2. As the person jumps they are going to move in a diagonal direction. To find how long the person is in the air before hitting the ground, you use the vertical equation for distance:

d = 1/2gt^2
45 = 1/2 (10)t^2
9 = t^2
3 = t

So the person is in the air for 3 sec. To find how far away the person is from the cliff when they hit the ground, you use the horizontal equation v = d/t. Since you are trying to find how far it is away from the cliff, you ignore the vertical distance and just find the horizontal distance. You know that the person is traveling at a constant velocity of 10m/s, and you know what the time, so just plug it in:

v =d/t
10 = d/3
d = 30m

You now know that the distance the person traveled is 30m in 3sec. Now the hardest part I believe is finding the velocity. For this, you use an equation from geometry. You know the vertical and the horizontal velocity, so to find the diagonal velocity, the velocity you are actually moving at a certain point, you use a^2 + b^2 = c^2. So lets find the velocity the person was moving at 1 seconds:

a^2 + b^2 = c^2

10^2 + 10^2 = c^2
100 + 100 = c^2
200 +c^2
c = 14.1m/s

Free Fall- Throwing things up at an Angle:

The last thing we learned in our unit about Newtons 2nd law was throwing things up at an angle like a baseball player. To the right, there is a picture of a baseball player throwing a ball will an initial vertical velocity of 30m/s, and a horizontal velocity of 5m/s with 1 second intervals between them. We know that the ball will continue to travel 5m/s in the horizontal direction, but in the vertical direction, the ball will start slowing down, therefore the vertical speed will go from 30 to 20 to 10 to 0, and then start speeding up again as it starts falling down. To find how far downfield the ball travels, you will use the horizontal equation v = d/t:

v = d/t
5 = d/6
d = 30m

We can also find how high the ball got at the top of its path using the vertical equation. Be careful because the vertical equation is meant for things falling down, so we will use it in terms of it falling down:

d = 1/2gt^2
d = 1/2 (10)(3)^2
d = 5 x 9
d = 45m

Just by looking at the picture we know that the ball is in the air for a total of 6 seconds. And we also know by drawing a picture that at the top of its path, the ball is moving 5m/s because it is always moving 5m/s horizontally.

To summarize the unit, I put together all of the equations that are needed involving vertical direction at constant acceleration, and horizontally at constant velocity:

What I have found difficult about what I've studied:

During this unit, I found it difficult to grasp all of the concepts. I would do fine during class, but then go and try to do the homework and find it very difficult. I missed quite a few classes as well, which made it even more difficult. I overcame these difficulties by trying to come in during me free, and I also used my peers around me well. I put in quite a lot of effort towards labs and class. And after a while, as I started to really use the resources around me, I found that things were starting to make more sense. Something I would like to start doing in the upcoming units, is start my blog reflection during the unit. I think this will help me because I will be able to summarize what I know, but at the same time, it will help me to realize what I don't know. I would use this to help me study for quizzes, and it will also help me to ask better questions.

A connection I made to the real world is diving in swimming. I know understand why when swimmers dive, they need a lot of force in the horizontal direction in order to be able to get out faster. I guess now I should be able to have the perfect dive off the block!

Falling Through the Air

In this video of Felix Baumgartner's jump from 24 miles of the ground, he demonstrates free fall when he is falling towards the earth. Baumgartner reached an estimated speed of 1,342.8 km/h jumping from the stratosphere, which made him the first man to break the speed of sound in freefall. Baumgartner was no longer in free fall when he opened his parachute. When he first jumped out, he started gaining speed very quickly, and once he reached terminal velocity, he continued at that speed until he opened his parachute.

 http://youtu.be/kBrD7CDKeA0?t=1m13s

Newton's Second Law Resource

In this video, the idea of Newton's Second Law is introduced. It talks first about what the law is and then goes on to explain everyday example in real life, such as being pushed on a swing or hitting an object. This video helped me because I was able to see Newtons Second Law being applied in situations I am in everyday. I was able to apply what I knew from the lab and then add on to that by seeing these examples and how they are directly related. 

Unit 1 Reflection

In this unit I learned about...

We started off learning about Newton's 1st Law of motion, which states that,

An object in motion will stay in motion, and an object at rest will stay at rest, unless acted on by an outside force

This meaning that once something is in a state of motion, it will continue to move unless something such as the force of gravity slows it down, or it hits a wall. An example of this is the classic trick of pulling a table cloth out from under plates. This demonstrates that the plates which are at rest want to continue being at rest even when the table cloth is pulled out from under them. We demonstrated this law during the hovercraft lab when we were at rest until we were pushed by our classmates, which was hard, because our mass was making it hard to leave the state of being in rest to being in motion. Once we were in motion we continued to move because there was nothing to stop us (the frictionless environment made it so that we didn't

slow down). This lab also touched on inertia, which is, the apparent resistance of an object to change its state if motion. Mass is the measure of inertia. During this lab, we also learned about equilibrium. At equilibrium, an object can either be moving at constant velocity or at rest. During the lab, the hovercraft was at equilibrium twice. In the picture of the 3 phases, phase 2 is an example of being at equilibrium, and then again when the hovercraft was completely stopped and at rest. During phase 1 and 3, the hovercraft was accelerating, while during phase 2, the hovercraft was at constant velocity. We learned that equilibrium is,

When something is moving at constant velocity or at rest, the net force adds up to 0 Newtons.

Force, which is a push or a pull, is measured in Newtons. The Net force is the total force, every push or pull adds up to make the total net force. For example, in the picture with the 2 pink people pushing the box in opposite directions, you subtract the 10N that are being pushed to the right, minus the 10N being pushed to the left to get a net force of 0N. So in this case, the net force is 0N which is equilibrium. In another example, the 2 orange people pushing the box left with 10N and right with 15N will have a net force of 5N. To get 5N, I subtracted the 15 minus the 10 to get 5N which is not equilibrium. Anytime there is a net force on something, it means it is accelerating. An example of this is when a box is being pushed with 50N to the left, and 50N to the right. The net force of the box is 0N, but that doesn't mean the box isn't accelerating. This just means that the box is either at rest or moving at constant velocity. I found interesting that during the hovercraft lab, we learned that it is possible to be accelerating in one direction, but being forced in the other direction. This is possible when a car comes to a stop, and involves Newton's first law: Since the car is in motion and suddenly comes to a stop, people in the car lurch forward because they are in a state of motion and are going forward while the force of the car stopping is making them stop. This happened when our classmates stopped us when we were on the hovercraft. An ilistration is shown below in the third example.

After learning about Newton's 1st Law, equilibrium, net force, inertia and acceleration, we moved on to learn about speed and velocity. This is where we learned our first equation for speed:

Speed = Distance  (s = d)
                Time             t

Speed and velocity are the same thing in the sense that they both are measured in distance over time, but velocity is different because it requires a specific direction. Arrows are used to know the direction of how great the velocity is, while speed doesn't need arrows. You can have the same speed, but not the same velocity because of the direction. A change in the direction means a change in velocity which means is is accelerating. And with that, we learned another equation. The next equation we learned was for acceleration,

Acceleration = Change in Velocity  (a = Δv)
                            Time Interval                  t

In order to get the change in velocity, there must be one of three: changing direction, speeding up, slowing down. All of which are acceleration because they happen over a time interval. Change in velocity is found by subtracting the initial velocity by the finial velocity. In the picture to the left, there is a ramp that goes down straight. In this diagram, the ball starts off at 0m/s and as it rolls down the ramp, it picks up speed, going from 0 to 2 to 4 to 6m/s. This speed is consistent, meaning that as the ball rolls down, it is picking up speed covering a larger amount of distance per second but increasing in a uniform way, 2m/s^2. This is called constant acceleration. In the next diagram, the ramp is curved. The ball once again starts off at 0m/s, but as it continues to roll, it again increases speed just not as consistent as the previous ramp. This ramp goes from 0 to 8 to 12 to 13, meaning that it still increasing speed, but now picking up speed slower, increasing by 8m/s^2 the 1st second and only 4m/s^2 the 2nd second, and then only 1m/s^2 increase the 3rd second. This is an example of decreasing acceleration.

The last 2 equations are for constant acceleration: how fast and object is going, and how far it goes,

V = at    and    d = (1/2)at^2 

We used these equations for or 2nd lab on "Comparing Constant Velocity to Constant Acceleration". We used a flat surface to roll a marble starting from 0m/s. On the flat surface, the marble rolled consistently covering the same amount of distance every 1/2 second demonstrating constant velocity. In the next experiment, we rolled the marble on a tilted surface and made a mark every 1/2 second. This time, the marble continued to pick up speed. Every half second, the marble was covering an increasing distance. This demonstrated constant acceleration. In the first chart to the right, the data represents the marble that was rolled on a flat surface. It shows how it was staying at a constant speed on average, covering the same amount of distance every half second. In the chart to the left, there is data for the marble that was rolled on a tilted surface. This data shows how the marble was increasing its speed every half second.

In this lab, we also learned about the equation for a straight line, where y = units on y axis, m = slope (change in y/ change in x), x = units on a axis, and b = where the line crosses the y axis,

y = mx + b

Reflection on the unit, I put together all of the equations that involve finding constant velocity, constant acceleration and acceleration,

What I have found difficult about what I've studied is...
        Comprehending the concept of inertia, it had been a struggle to understand completely what inertia is and how it is supposed to be used. During class I have had to ask classmates and Mrs. Lawrence, and it did not click until we were assigned a podcast about inertia. My group prepared a video explaining inertia and it helped me when I heard it coming from my group, putting it into words and then into a video. I also watched other students podcasts about inertia in other classes and it helped me to get a more solid idea of what inertia is and how I can apply it to everyday life.

       I have found that during physics thus far, I have been able to apply my skills and effort in a way that has benefited for the most part. During labs and class discussions, I have been able to ask questions and contribute my ideas in order for myself and my classmates to understand the material more deeply. During problem solving questions, I have tried to persist in order to find the right answer, but I have struggled a little in the way I apply what I have learned to the question. But, during class, I am able to apply what I have learned, and put it into words to help classmates to understand it. So, something I need to work on is the way I apply what I have learned into the way I work to find answers. Something I have done a great job in this year is using my self confidence in class to work around difficult things in labs and in group activities. I have shown confidence and taken charge in situations and have been able to work around difficult questions. This confidence has helped me to collaborate with group members, and this has helped in getting things done. My goals for next unit will be to be more persistent and pay attention to details, something I struggled with when trying to complete the acceleration problem solving worksheet. Striving for good problem solving skills is something I hope will be accomplished next unit, which will help my understanding of physics as well.

Connections to the real world..

       This past weekend I had an unexpected run in with Newton's first law. I had put my rubbish in a trash bag and placed it in the corner. I then began vacuuming my room. I meant to nudge the trash bag further in the corner in order to vacuum more area, but instead, the vacuum sucked up the trash bag and left all my rubbish on the floor. I related this to Newton's first law because my trash bag and rubbish were at rest in the corner until a force came (the vacuum) and sucked up the bag, making it leave its state of rest. The rubbish continued to stay in a state of rest even when the bag was moved, therefore, the rubbish was not sucked into the vacuum along with the bag, it simple stayed at rest and all fell to the floor, demonstrating inertia which is a property of motion. 

Constant Velocity vs. Constant Acceleration Lab

During the Constant Velocity vs. Constant Acceleration lab, I learned how constant velocity and constant acceleration are very different in the sense that constant velocity continues at the same pace while constant acceleration continues at an increasing speed. Yet, both constant velocity and constant acceleration are similar in the way that they are needed for both. Constant Velocity is when the is when an object is covering the same amount of distance per second. It is moving with a consistent speed. Constant Acceleration is when the speed is either constantly increasing or constantly decreasing. The object is covering either a consistently increasing or decreasing amount of distance per second. 

In this lab, we used a marble and a table. The first experiment we conducted involved constant velocity, and for us to do this, we used a 1/2 a second timer that beeped every 1/2 second. We used a flat surface to roll the marble, and we started off with the marble in a state of rest. We pushed the ball and for every time the 1/2 second timer went off, we made a chalk mark where the marble was at that moment. This demonstrated constant velocity because our chalk marks were evenly spaced out showing that the marble covered the same amount of distance for every half second. For the second part of the lab, we demonstrated constant acceleration by putting the table at a tilt, making it resemble a ramp. We preformed the same task at we did in order to demonstrate constant velocity, but this time when we made chalk marks they were not evenly spaced. For this part of the experiment, the chalk marks were consistently spaced farther and farther apart, showing that constant acceleration increases its  speed at a constant rate, covering a larger amount of distance per half second.

The equation used for constant velocity is velocity equals acceleration multiplied by time. While the equation for acceleration is the change in velocity divided by the time interval. We took our results from our velocity lab and made a graph. The graph came up with a perfectly straight  line, with an equal distance between each point, showing the consistency of the marble rolling with a constant velocity. We then took our results from the constant acceleration lab and made a graph. The constant acceleration results made a graph that curved upward, showing how there was more distance being covered for every half second. Once I put my results into excel and got an equation, I plugged in a number representing time in seconds for the x. I solved for x, and I ended up with an answer that was on the line that I graphed.

In this lab, I learned a lot about the difference between constant acceleration and constant velocity. I realized when making the marks with chalk, that I had to go back a couple of times and repeat the experiment in order to get concrete results. In future labs, I will have to be able to do the experiment a few times in order to back up my evidence. Connecting to this, I will have to be able to manage my time wisely in order to get the entire lab done, as this was something that came up when I was rushing at the end in order to finish everything. In these labs, I am having fun, but at the same time I'm learning a lot. I was able to enjoy the lab and be able to understand things better, something that I hope I will be able to do in future labs.

Speed and Velocity

In this song by They Might Be Giants, the difference between speed and velocity is explained. It shows an airplane taking off and flying in the air. This is both speed and velocity. Speed because it is going 500 miles per hour, and while its velocity is also 500 miles per hour, its velocity is actually 500 mph in the western direction. This demonstration shows:

Speed = 500 mph
Velocity = 500 mph west

Post Hovercraft Inertia Lab

Post Hovercraft Blog Post

a.) Riding on a hovercraft feels like you are floating, and as you glide, you are in a frictionless environment and your velocity stays that same, making the gliding continue at the speed you are going. Riding a sled or a skateboard is different because when riding those objects, you can pick up speed, but eventually your speed will decrease and you will come to a stop because of the friction. Unlike riding a sled or skateboard, the hovercraft continues at a constant speed and never stops or slows down unless a force intervenes.

b.) The hovercraft helps demonstrate inertia is the sense that the hovercraft had to be pushed out of its state of rest to start moving, and the only way to slow it down was to use force and stop it, putting it in a state of rest. The hovercraft also demonstrated equilibrium when the net force equaled 0N in two situations: it was moving at a constant velocity or when it was at rest.

c.) In the hovercraft lab, acceleration was demonstrated when someone was pushing the hovercraft or when someone was stoping the hovercraft. In these situations, the hovercraft was speeding up in the beginning and slowing down when stopped.

d.) In the lab, after being pushed off, the hovercraft was in a frictionless environment, thus making it so that it would continue at a constant velocity. The speed stayed that same, and would have continued to stay the same if a force had not stopped it (the force in this situation being the person who stopped the hovercraft).

e.) During the hovercraft lab, some members of the class were harder to start and stop than others, this being because people with more mass have more inertia, therefore they are harder to get started because the state they are in of either rest or motion wants to continue being in this state. 

7 Inertia Demonstrations