Unit 1 Review: Test

In this unit, the major concepts were: Newton's 1st Law, Inertia, Net Force and Equilibrium, Acceleration, Velocity, and how to tell Acceleration and Velocity apart using different equations for each.

Newton's 1st Law is that an object in motion will stay in motion unless acted upon by an outside force and an object at rest will stay at rest unless acted upon by an outside force. For example, table settings are on the table with the tablecloth underneath. The settings on the table are at rest. When the tablecloth is removed from under the settings, the settings will stay at rest because of Newton's 1st Law, which states that an object rest will stay at rest unless acted upon by an outside force. 

As shown on the video, the girl removes the tablecloth and the settings (the bowl) stays in place because of Newton's 1st Law.
We can see Newton's 1st Law in everyday life when we accidentally leave our coffee cups on the top of our cars. The coffee cup is at rest on top of the car. When the car accelerates forward, the car is removed from under the cup (just life the tablecloth example). The cup falls exactly underneath was it was on the car because of Newton's 1st Law, which says an object at rest will stay at rest unless acted upon by an outside force.

Inertia goes along with Newton's Law because it's basically saying that objects like to keep on doing what they're already doing, unless a force is acted upon to make it change. For example, when on the hovercraft we needed a force to move us from our position at rest (at the beginning) and a force to stop us from moving (at the end). During this experiment, we learned that the more mass you have that more inertia you have. Because when trying to stop the hovercraft, it was harder to stop for those that had more mass, but it was easier for those who had less, which means that your mass depends on your inertia.

While on the hovercraft, we had a feel for what equilibrium was. When we were at rest, we were at equilibrium and when we were moving at a constant speed we were also at equilibrium. An object is at equilibrium when it is either at constant velocity (no speed or the same rate) or when the object is at rest. Something that's important to know about an object being at equilibrium is that when at equilibrium the net force will be 0N. Net Force is the force pushing against an object or the force at which it is at rest. When at object is at constant velocity, the force of friction (going on direction) will be equal to the amount pushing the opposite direction.

In this picture, there are 50N pushing to the left and 50 N pushing to the right. Because there are an equal amount on each side the net force is 0N and the object is at equilibrium. 

Acceleration is the change in velocity over a period of time. You can change your velocity in 3 different ways: speeding up, slowing down, and changing direction. If there is no change in velocity, there is no acceleration. I always forget that change in velocity is change your direction, so easy way to remember is that they are both "changing."Acceleration happens in everyday life when you're changing your speed in a car or when you're walking. Acceleration is measured is m/s^2. If an object is at constant acceleration, there are two different formulas used for measuring how fast and how far the object is going. How fast is velocity equals acceleration x time. How far is distance equals 1/2 acceleration x time ^2.

If a ball is rolling on a flat surface:

Then the velocity is constant and there is no acceleration, 0 m/s^2

If a ball is rolling down an inclined ramp:

Then the velocity and the acceleration are increasing.

If a ball is rolling down a curved ramp:

Then the velocity is increasing, but the acceleration is decreasing.

If an object is free falling, then it is going at 10 m/s^2

If a car is traveling at a constant speed, then it is traveling with a constant velocity. When at constant velocity, then the acceleration is 0 m/s ^2. The equation for constant velocity is velocity = distance / time. Even if an equation asks for how fast or how fast a car, or an object, is going, if it is going at a constant speed, then it is automatically going at a constant velocity. 

If something has constant velocity then it cannot have constant acceleration because with constant velocity you're covering the same amount of distance with the same amount of time. But with constant acceleration you're speeding up.

When studying this section, I found figuring out when an object has velocity and when it has acceleration difficult. However, the diagrams (shown above) made it easier to understand.