Lab –Conservation of Mechanical Energy
I.
Purpose:
The purpose of this lab was to investigate the conservation of mechanical energy using a
roller coaster to show that energy is constant/conserved but can change forms.
II.
Materials:
CPO roller coaster track, physics stand, timer, photo gate, stainless steel marble, meter
stick, lab paper, pencil, triple beam balance.
III.
Procedure:
1. Gather materials listed above.
2. Find the mass of the marble.
3. Assemble the rollercoaster.
4. Use the meter stick to measure the height from the top of the lab bench to the center of
the marble at a number of positions on the roller coaster track, corresponding to the chart
on the lab sheet.
5. Record this height on the data table.
6. Plug in and power on the photo gate. Set timer to “interval”.
7. Place the photo gate on the corresponding spot. Let the marble pass through. Record
the time on the data table.
8. Using results, calculate the speed, potential energy, and kinetic energy. Graph the data.
(Speed vs. Position and Height vs. Position)
IV.
Analysis:
Equations used: Speed = Distance/Time
Change in Potential Energy = mgh
Change in Kinetic Energy = (.5)(m)(v)2
1. After looking at the graph, I can conclude that as the height drops, the speed
increases, and as the height increases, the speed decreases. The speed is like a
reflection of the height. The speed will change oppositely according to the height.
2. The height is potential energy since the higher the marble is, there is more stored
energy to fall and convert to kinetic energy. Speed is a variable of kinetic energy
since the kinetic energy is motion and speed is an equal representation.
3. When potential energy is high, the kinetic energy is low. When kinetic energy is high,
potential energy is low.
4. When the height is higher, there is a larger potential energy since the speed is lower
and there is more stored energy to fall. This also means that the kinetic energy is
much lower. When the height is low, the potential energy is lower. This is because the
speed is higher which means there is more kinetic energy. Also the potential energy
has been converted to kinetic energy. The relationship between kinetic and potential
energy were opposites, when one is high, the other is low. This fits with the law of
conservation of energy because the energy is not being created or destroyed; rather, it
is just being transferred from potential to kinetic. The energy is always constant and
equal. Some variances in the data may have resulted from mistaken data recording for
errors in the lab.
V.
Conclusion:
The objective of the lab was to see how the law of conservation of energy was true and
that energy is never created or destroyed. It can only transform into a different form. In this lab I
saw that the potential and kinetic energy were constants. As potential energy increases or
decreases, kinetic energy increases or decreases oppositely and correspondingly to potential
energy. This can also be reversed. This is because the potential and kinetic energy are being
converted from one to another.
The possible errors in the lab may have come from the inaccuracy of placing the photo
gate. Also when assembling the roller coaster, the slide did not fit tightly with the stand and
would slip out. Sometimes our group would forget to hold onto the slide. The shaking of the
slide could have changed the true results of the data. Also rounding the results did not give us
precise data. Also an average time should be calculated for each position to get an accurate time.
Our group had tried one position on the roller coaster twice and different times were given.
Through this lab, I discovered that energy is never created or destroyed, but changing
forms. I learned that the mechanical energy of potential and kinetic energy are constant and
equals. As one goes down the other goes up. (Reversible). We apply this conservation of energy
to everything we do. All our actions have stored potential energy, once we move, that potential
energy is converted into kinetic energy. For example when we are sliding down a slide. At the
top, we are not moving, but we have stored potential energy. When we go down the slide, that
potential energy is converted to kinetic energy as we speed up.