What Did We Learn in Unit 1

What Did We Learn in Unit 1? 

Physics starts with forces and how they act on things.

The first concept adresses Newton's first law which is that: an object at rest will stay at rest and an object in motion will stay in motion unless acted upon by an outside force. Inertia describes an objects tendency to resist a change in rest or motion. Mass is a measure of Inertia. it may seem as though Inertia can be a measure of Mass because we are familiar with Mass first, however, it is the other way around.  An example of Inertia is suppose you have a refrigerator and a soccer ball. You try to move them both 10 meters, but it is very hard to move the refrigerator, and easy to move the soccer ball. The Inertia of the refrigerator is greater because it has more resistance to change it's state at rest.

Net Force and Equilibrium:

A force is either a push or a pull that acts on an object. The force is measured in Newtons(N). The Net Force is the sum of all of the forces acting on an object. If an object is at equilibrium, that means the Net force is zero. An object can be at equilibrium when it is at constant velocity or at rest. 

Example Question:

If I push on a box from one side with a force of 100N, and Caroline pushes on the other side with a force of 75N, what is the Net Force? Is the box at equilibrium?

Answer: 25N, no

Velocity and Speed:

Speed is a measurement of how fast an object is going. You measure speed by covering and objects distance in a period of time. An easily understood example of this is how we measure the speed of out cars- in Miles per Hour. As in, how many miles(distance) is the car covering in a period of time (miles).

Velocity is more specific because it refers not only to the distance in time, but also to the direction. An object can maintain speed, but change velocity by changing it's direction. This is because it takes an acting force to change direction. An example to think about is riding a bike around a baseball field. If you follow the perimeter, you can keep the same speed, but since your direction is constantly changing, your velocity is not constant.

There are two ways to change velocity: speed up/slow down, or change direction

The direction portion of velocity is shown using vectors, which are basically arrows. They convey both the magnitude, or the speed of the velocity and the direction.


Acceleration:

Acceleration is a change in velocity over a period of time. Speeding up is acceleration, but slowing down is also acceleration but in the opposite direction. Acceleration is measured in meters per second squared rather than just meters per second. If an object is falling straight down, the acceleration is always 10m/s squared.

Constant Acceleration and Velocity: Constant Velocity is when for any given time the speed and direction are the same. Constant Acceleration is when an object is speeding up or slowing down the same amount each second. Constant Velocity and Constant Acceleration are mutually exclusive. 

 Calculations:

https://www.youtube.com/watch?v=O2yG-5yiuhQ&feature=youtu.be


To calculate Acceleration you will need three formulas:

The equation for acceleration: acceleration = change in V/time

Distance:      d=1/2 a t^2
Speed(how fast):  v=at

Formulas for Velocity:

v = d/t
d = vt

Learn Them!