# PHYS 1110/2010 Midterm 2 Study Guide

## Quick recap of Force Problems

1. Write down knowns + unknowns

2. Draw a picture

3. Choose a coordinate system + Usually x is horizontal, y is vertical + For ramps choose x to be down the ramp and y to be perpendicular to the ramp

4. Draw a free body diagram!!

5. Write down sum of forces from tree body diagram 6. Is the acceleration in the x or y direction 0?

7. Use force equations to solve for unknowns!

## Work + Energy

Work-Energy Theorem: "Work done equals change in kinetic energy"

How to calculate work done by forces: Work done on an object in circular motion is always zero!

Conservation of Energy: “Energy in the beginning equals energy in the end”

If there’s kinetic and potential at the beginning and only kinetic at the end, then: Just an example, it won’t always look like this

## Power ## Gravity

Force of gravity If we cross out the little m’s, we get the gravitational acceleration on a planet: ## Momentum

Momentum is ALWAYS conserved!!! (The lines on the top just mean that they're vectors)

Momentum of one object is + Notice that momentum is a vector that points in the same direction as velocity

+ If you want to add two momentums, you have to do vector addition  ## Alex Koek

January 11, 2020

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