How do potential and kinetic energy apply to the law of

Question

Section 1 - From the left of the screen to the right, the red balls have a center of mass placed at 20 feet, 15 feet, and 10 feet high respectively.

1. Suppose each red ball weighs 20 lbs.  Find the potential energy (PE) for each ball on each ramp.  In this lab mass is given in pounds and height is in feet, so use 32.2 ft/sec² as the gravitational constant.  Your answer will be in foot-pounds since US units are being used.

PE = mgh where g = 32.2 ft/sec²

Ramp 1:

Ramp 2:

Ramp 3:

2. Predict the maximum speed (velocity) of each ball on each ramp.  How would this speed change if each ball's mass was doubled?

ASSUMPTION: assume there is no friction and that all the potential energy you calculated in question 1 is transformed into kinetic energy- PE = KE.  Use the following equation.

KE= ½ m v² 

You want to calculate v maximum speed

v = [KE/ ½ m]^½

This means divide the KE by half the mass and then take the square root.

	Max v for 20 lb. ball	Max v for 40 lb. ball
Ramp 1
Ramp 2
Ramp 3

Section 2 (Each of the green balls has a center of mass placed at 20 feet high).  While each ramp looks identical, each ramp has a different amount of friction. 

3. Which ramp has the greatest friction?

4. Suppose each green ball weighs 10 lbs.  Assuming there is no friction, calculate the potential energy for each ball on each ramp.

5. Again assuming there is no friction; predict the maximum speed of the ball on each ramp.  On which ramp does the ball come closest to achieving this max speed?

Use this table to organize your calculated values

	PE	Max Seed (v)
Ramp 1
Ramp 2
Ramp 3

Part II - For the following questions, provide your response in short answer format (2-3 sentences each). Use this Phase's activities and resources to assist you in answering:

6. What is Potential Energy (PE)?

7. What is Kinetic Energy (KE)?

8. What is Inertia?

9. What is Gravity? How is it a type of potential energy?

10. What is Mass and how does it affect energy?

11. How do Potential and Kinetic energy (gravity and mechanical force) apply to the Law of Conservation of Energy?

12. What is Friction? How does it affect energy use?