Unit 1 Review

In this first unit, I learned many things. I learned about force with Newton's first law and how to apply it in everyday life, like I did when I rode the hover craft, net force, and equilibrium, all of these are subtopics of Inertia. I also learned about constant velocity, constant acceleration, and how to use the equation of a line (a graph) to solve problems for both of these topics.

Inertia

In this area of the unit, I learned about Inertia and force. Mass is the measure of Inertia, in kilograms. 

Force is either a push or a pull, and it's measured in Newtons (N), which equals 1/4 of a pound. An object that is being pushed with 5 Newtons to the left, that object will be moving to the left, and have a net force of 5 N to the left. Whenever you have forces on opposite sides of an object, you subtract both sides Newtons from each other to find the total net force. If the forces are on the same side, you add them. Another example of an object with force is the hovercraft; the hovercraft was at constant velocity, meaning it never sped up, slowed down, or changed direction, and the net force was 0 N. If something is at constant velocity and/or have 0N, it's at a stage called equilibrium. This object could be at rest or moving at a constant velocity.

Another thing in Inertia I learned was the force of friction. If friend A pushed a box that's at rest with 100N and it didn't move, what is the force of friction? The force of friction would also be 100N because to stay at rest/equilibrium, the box would have to equal a total amount of 0N (100N-100N=0N)
One of the big things we learned in Inertia is Newton's first law. His first law is: an object in motion/rest, tends to stay in motion/rest unless acted upon an outside force. A big question I always received was; I left my coffee on the trunk of my car, when I took off it falls to the ground at the exact spot it was above the ground on my car trunk, why? The answer is that the coffee is at rest on my trunk, so when I take off, the force under it (the car) swipes from under it, not strong enough/too fast to keep it on the trunk, leaving the cup to fall right there. This explains Newton's first law of an object at rest tends to stay at rest unless acted upon another force. The coffee was the object at rest, and the car moving from under it was the weak/fast force. Another example is this graduated cylinder skateboarding:

Here the rock (outside force) stops the skateboard (the object in motion), and causes the graduated cylinder to keep on moving, because the rock wasn't big enough to stop him too.

Speed & Constant Velocity

Speed is the movement of an object at a pace that's fast or slow. I learned that constant velocity is going at a certain speed the whole time through the process. Constant velocity relies on 2 things: 1. constant speed. 2. One certain direction. This means that if you speed up, slow down, or turn, you will not be in constant velocity. I learned that to measure velocity it's meters over seconds (m/s). We measure velocity by the distance over the amount of time (v=d/t). Objects can be at a constant speed, and sometimes at a constant velocity, because they could be turning, but if they weren't then they are at constant velocity. Constant velocity has certain formulas to find the distance and speed for when an object has constant velocity. The distance equation is: d=vt, and the speed formula is the same as the constant velocity one which is v=d/t.

An example of constant velocity is me driving my car. I drive my car for 5 seconds and went 600 meters, how fast was I going? Well, if I use the constant velocity formula, v=d/t, I can plug in 600 for d, and 5 for time, and get 120m/s. If I was driving again for 12 seconds at a constant velocity/speed of 40m/s, how far did I go? Same thing, use the distance formula, d=vt, d=40(12), which is 480 meters. If I turned my car around and around, at a constant speed, I wouldn't be going at a constant velocity because I'm changing direction.

Constant Acceleration

Acceleration is the speeding up and/or slowing down of an object. Constant acceleration is calculated by the change in velocity over the time interval (^v/t=a [^=a triangle=change in]). Acceleration is in the units of meters per second squared (m/s^2). Just like velocity, we can use formulas to find how far and fast something was going/in a certain acceleration.

Here you can see this car acceleration at a constant acceleration of 2m/s^2. It started at a speed of 0, so every second it accelerated 2m, so by the time of 5 seconds it was going 10m/s. This is our speed/velocity formula we use: v=at. You plug in 2 for a and 5 for t, so 5 doubled is 10. We can also see how far it went after 5 seconds. The distance formula for constant acceleration is d=1/2at^2. If you plug in 2 for a and 5 for t again, solve it, you can see that the car went 25 meters.

Here are 3 ramps, the ramp on the left is a constant accelerating ramp because it slopes down perfectly to have a constant acceleration. The middle ramp has a decreasing acceleration because as a ball goes down the ramp, the ramp gets bigger, so therefore it has a decreasing acceleration. The last ramp is one that drops completely, making the acceleration increase.

Using a Graph (Equation of a Line) To Solve Physics Problems.

Here I learned that with certain graphs with equations of lines I can find the constant velocity, acceleration, and distance an object was going. 

If I was given an equation of y=4x, I can see this equation is close to the velocity equation of d=vt. On the graph, the y-axis is distance, and the x-axis is time, so I plug that into the equation of the line to get: d=4t. I can see that 4 is the constant velocity and I can plug in any time to find the distance.

Using the same equation for a constant acceleration graph, I can see that it's close to the distance formula for constant acceleration too. Plug the values in again; d=4t^2, but wait, where's the 1/2 you might ask. The acceleration is already halved, so to find the actual acceleration, you just double the number there, so in his case the acceleration would be 8m/s^2.

Here is more information/a video of how to do this in more depth:

All of this is what I learned from my first unit in Physics! I really like this class and hope to learn more new and cool subjects like these.

Hovercraft Questions

1. Riding ob the hovercraft was fun and what it did was make a loud noise, vibrate a little, and slide smoothly across the floor. I would tell anyone to try riding a hovercraft because it was cool and an experience that everyone should have done. Riding a skateboard and sled is different because it wouldn't keep in motion with all the friction under it.
2. I learned that the hovercraft kept going because of inertia, Newton's first law; an object in motion tends to stay in motion unless acted upon another force. The hovercraft was at equilibrium when it was moving at a constant velocity, with 0Newtons. Also when we were stopped (at rest).
3. Acceleration seems to depend on the amount of force being pushed or pulled, and this force helps the acceleration speed up/increase.
4. I was having/in constant velocity when I kept moving across the floor on the hovercraft in a straight line at the same amount of force from first push.
5. Some members were harder to push or move because of their weight. If they were heavier, it would take/we would have to make/do a bigger force to push and move them across the floor and hover.
6. Picture:

Inertia

In this video, one of the demonstrations was the guy pulled back the chair with a stack of books on it and pushed it against another chair. What happened was the moving chair hit the other chair causing the moving chair to stop and the books to keep going yet stay on top of each other, then they crashed into the wall to fully stop. That demonstration showed Newton's law of an object in motion tends to stay in motion unless stopped by a force. The object in motion was the chair with/and books, and the force that stopped the chair was the other chair, but the force that stopped the books was the wall, and they stayed on each other.