Conservation of Energy
Mr. Sabor
Introduction: We will be investigating the Law of Conservation of Energy. The Law of
Conservation of Energy states that energy cannot be created or destroyed. We will investigate
the Law of Conservation of Energy by dropping a soccer ball under a motion detector. The
motion detector will measure the distance the ball drops over time. It will also measure the
speed of the ball as it drops. From this, we will be able to calculate the potential and kinetic
energy of the ball at any one time. The kinetic energy is the energy of motion and potential
energy is the energy of position. We will be analyzing the gravitational potential energy. If our
hypothesis is correct, the potential energy will become kinetic energy as the ball drops. The
amount of potential energy is loses will be the same as the amount of energy it gains.
Objective: Investigate conservation of energy.
Variables: The independent variables for the lab were the height from which the ball was
dropped, the interval over which the ball’s motion was measured, and the fact that we used a
soccer ball in the lab. The dependent variables were the position and speed of the ball at certain
time intervals.
Hypothesis: As the ball drops, if the total amount of energy stays the same, then the Law of
Conservation of Energy is proven.
Procedure: Our lab went as planned according the directions given to us. We did have to limit
the number of data points from the original nine. We recorded only seven.
Data: See other side.
Analysis:
See other side for calculations.
1. The ball has potential energy at the top of its path.
2. The ball has kinetic energy at the bottom of its path.
3. The potential energy changes to kinetic energy as it drops.
4. The total energy will not change on the way down, allowing for slight variations. This is
because the sum of the potential and kinetic energy always added up to the same value, which is
what the Law of Conservation of Energy predicts.
5. The amount of kinetic energy the ball gained on the way down was equal to the amount of
work done by gravity.
6. If the wrong mass was entered all of our values would be off but the total energy would be the
same as it dropped.
Conclusion:
Our data showed that the total energy stayed the same as the ball dropped therefore our
hypothesis is correct. The Law of Conservation of Energy was confirmed.
Position
Number
1
2
3
4
5
6
7
8
9
Time
(s)
Position
(m)
1.4
1.45
1.5
1.55
1.6
1.65
1.7
1.75
1.8
0.178
0.178
0.18
0.218
0.324
0.449
0.598
0.774
0.969
Mass of Ball (kg) =
0.4285
Speed
(m/s)
0.023
0.156
0.592
1.407
2.185
2.736
3.239
3.708
4.055
Height
(m)
0.791
0.791
0.789
0.751
0.645
0.52
0.371
0.195
0
Sample Calculations:
KE = speed squared * ½ * mass
PE = mass * 9.8 * height
Work = mass * 9.8 * position
Total Energy = KE + PE
Kinetic
Energy (J)
Potential
Energy (J)
Work (J)
Total Energy
(J)
0.00011334
0.00521399
0.07508691
0.4241398
1.02287771
1.60381037
2.24772267
2.94577981
3.52291811
3.3216463
3.3216463
3.3132477
3.1536743
2.7085485
2.183636
1.5579403
0.8188635
0
0.747475
0.747475
0.755874
0.915447
1.360573
1.885486
2.511181
3.250258
4.069122
3.32175964
3.32686029
3.38833461
3.5778141
3.73142621
3.78744637
3.80566297
3.76464331
3.52291811