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 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
Force of gravity
If we cross out the little m’s, we get the gravitational acceleration on a planet:
Momentum is ALWAYS conserved!!!
(The lines on 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