Conservation of Energy Lab
Name:____________________________________
Mod:_____________
Date:_____________
Pre-Lab Questions:
1. What is Mechanical Energy?
2. What is the main difference between kinetic and potential energy?
3. How does an object gain potential energy?
4. In the lab, what are the four drop heights for the metal spheres?
5. In the lab, how many trials should be completed for each height?
Purpose:
- To determine if the Total Mechanical Energy of a system is conserved.
Materials:
- Meter Sticks (2)
- Stopwatch
- Metal Sphere
- Balance
Theory:
In physics, energy (Greek meaning, "activity, operation") is a quantity that is often understood
as the ability a physical system has to produce changes on another physical system. The changes are
produced when the energy is transferred from a system to a different system. A system can transfer
energy by means of three ways, namely: physical or thermodynamically work, heat transfer, or mass
transfer.
In this lab, we will look precisely at the physical work done on the system. The system will be a
metal sphere that is dropped from different heights which will then be described through gravitational
potential energy and kinetic energy of the mass.
Procedure:
1. Take two meter sticks and place them on top of one another. Take the metal sphere and
drop it from a height of 2 meters.
2. One member of your group should hold the meter sticks; another group member drops the
spheres from a height of 2 meters and record the time of the fall. The third person should
record the data of the experiment.
3. Drop the metal sphere and repeat for 10 trials. Record in the data table under the 2 meter
column.
4. Repeat steps 2 and step 3 for the different heights at 1.5, 1.0 and 0.5 meters.
5. Calculate the average the times for each height and place record the data.
6. Calculate the final velocity of the metal sphere using the average time and the first
kinematic equation.
7. Measure the mass of the metal sphere. Mass is given in grams on the scale and must be
converted to kilograms.
8. Determine the Initial Potential Energy of the mass.
9. Determine the Final Kinetic Energy of the mass by plugging the final velocity into the Kinetic
Energy equation.
10. Calculate the % difference between the initial PE and the final KE.
Conservation of Energy Lab
Methacton High School Physics Department
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Data Table:
Mass of
Metal Sphere = _________________ kg
Trial #
Time at (2.0 m)
1
Time at (1.5 m)
Time at (1.0 m)
Time at (0.5 m)
2
3
4
5
6
7
8
9
10
Average Time:
(sec)
Final Velocity:
(m/s)
Initial PE:
PE = mgh (J)
Final KE:
KE = ½mv² (J)
% Error:
[(PE – KE)/PE] x
100
Conservation of Energy Lab
Methacton High School Physics Department
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Data Calculations:
Directions: Complete one worked out example for each topic below using the 2.0m drop height.
Final Velocity:
Initial PE:
Final KE:
% Error:
Post-Lab Questions:
Directions: Please answer all questions with complete sentences when necessary and show all work.
1. Is there any correlation between the person dropping the ball and timing it with its percent
error? Why or why not. What things can be done to decrease this percent error?
2. Was energy conserved between the initial potential energy and the final kinetic energy? Answer
yes or no and then explain what forms of energy the initial energy was transferred into.
Conservation of Energy Lab
Methacton High School Physics Department
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3. On the graphs below, show using a bar graph how the energy is transferred as the object falls
from PE to KE. Use only the data from the 2 meter ball drop to complete the data below as the
ball falls from 2 meters to 0 meters.
2m
PE
1.5m
KE
PE
.5m
PE
KE
Conservation of Energy Lab
Methacton High School Physics Department
1m
KE
PE
0m
PE
KE
KE
4