Kinetic/Potential Energy Lab
Introduction

Potential (stored) Energy can be converted to Kinetic (applied) Energy and back again.  We will use an inclined plane to convert the potential energy of a ball at the top of the ramp to a ball in motion at the bottom and then compare the potential energy we started with to the kinetic energy it was converted to when the ball was released.

Formulas: PE = mgh KE = 1/2mv2

Note: You will have to make a couple of conversions along the way:
Height must be given in meters, not centimeters.  Convert it by dividing by 100.
Mass must be given in kg, not grams.  Convert it by dividing by 1000.
Gravity (here on Earth anyway) = 9.8 m/s2

Procedure

Measure the mass of the marble and the ball bearing and record these on the data table.
Calculate the PE of each ball at each height in the data table.
Set up the ramp on the ringstand (as in the velocity lab) to the height specified in the data table.
Measure out the distance of the “track” from the end of the ramp to the “finish line” and record this on your data table.
Let the ball roll down the inclined plane and record the time it takes to travel the track.
Calculate the velocity for each run of the balls.
Calculate the KE to finish out the data table.

Results
Ball Bearing      Marble
Height (m)0.1  0.2    0.3      0.1        0.2         0.3

Mass of Ball (kg)_____    _____    _____    _____    _____    _____

Distance traveled (m)_____    _____    _____    _____    _____    _____

Time to travel (s)_____    _____    _____    _____    _____    _____

Velocity of ball (m/s)_____    _____    _____    _____    _____    _____

PE (J)_____    _____    _____    _____    _____    _____

KE (J)_____    _____    _____    _____    _____    _____
Graph:
Make a graph of the PE and KE vs. height.
Height (cm) = x-axis
Energy (J) = y-axis
Plot the PE data for the ball bearing with a solid round point.
Plot the PE data for the marble with a hollow round point.
Plot the KE data for the ball bearing with a solid square point.
Plot the KE data for the marble with a hollow square point.

Conclusions
How did the balls’ potential and kinetic energy change as the height of the inclined plane changed?
 
 
 

Which had more potential energy, the marble or the ball bearing?
 
 

Which had more kinetic energy?
 
 

What are some potential sources of error in this design?
 
 
 

What does this say about conservation of energy?


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