Mechanical Energy Lab
Part I
In this part of the investigation we will explore the properties of mechanical energy by analyzing a pendulum.
Purpose:


Utilize conservation of energy to calculate velocity of pendulum swing.
Discover the relationship between potential and kinetic energy.
Procedure:
1. Set up a pendulum on your desk using the string and hanging masses provided.
2. Measure the mass of the “hanging mass” and record your data in kilograms.
3. Set up pendulum with mass as close to the floor as possible without touching.
4. Pull up pendulum to desired drop height.
5. Measure the height of the pendulum by finding distance between floor and BOTTOM of the weight
6. Calculate the potential energy of the marble at the top of the pendulum swing.
7. Using concept of conservation of energy, calculate the velocity of the pendulum. (Hint = solve for the velocity
based on what you know about the relationship between PE and KE)
8. Repeat procedure with another size mass dropped from the exact same height.
Mass (kg)
Gravity (m/s2)
Height of Drop
(m)
Velocity (m/s)
Potential
Energy (J)
Kinetic Energy
(J)
Graph:
Sketch a graph with three independent lines in the same axis plot. The lines should represent kinetic energy,
potential energy, and total energy of a pendulum as it swings back and forth over time. Your graph should be a
visual representation of the energy transitions that occur ranging from 0% to 100% energy on the vertical y-axis.
Please label a color-coded key for each line to go along with the graph.
Extension:
1. Can you use a formula from physics to get a true measured value for the velocity of the pendulum to see if it
matches the theoretical calculated value in your data table? (Show all of your work in the process)
Mechanical Energy Lab
Part II
In this part of the investigation we will explore the properties of mechanical energy by analyzing an incline ramp.
Purpose:


Practice using the PE and KE equations to test the concept of conservation of energy on a ramp.
Analyze the relationship between potential and kinetic energy.
Procedure:
1.
2.
3.
4.
5.
Create a ramp using a standard ruler and a stack of books.
Measure the mass of a steel ball and record your data in kilograms
Place the steel ball at the top of the ramp and record the height of the position before releasing the ball.
Release the steel ball and start a stopwatch to time the ball as it moves down the ramp.
Calculate the potential energy of the ball at the top of the ramp and compare this to the calculated kinetic
energy at the bottom of the ramp in your data chart.
6. Repeat the procedure changing the height of the ramp.
Mass (kg)
Gravity
(m/s2)
Height of
Ramp (m)
Distance
Traveled
(m)
Time (s)
Velocity
(m/s)
Potential
Energy (J)
Kinetic
Energy (J)
Analysis Questions:
1.
2.
3.
4.
5.
How are potential energy and kinetic energy related?
What things could you do to cause a change in the potential energy for this experimental setup?
At what point was the potential energy of the pendulum the highest in this experiment?
At what point was the kinetic energy of the pendulum the highest in this experiment?
How tall should the ramp be if you wanted to create 1 Joule of potential energy using your ramp setup?
(Show work)
6. In theory, the potential energy at the top of the ramp should match the kinetic energy at the bottom of the
ramp. Based on your data, was 100% of the potential energy converted into kinetic energy in this test? If not,
where might it have gone? Are there any possible sources of experimental error or math misconceptions in your
work?
7. Explain how the law of conservation of energy and the concept of “work” apply to this energy lab.
Next year- compare theoretical velocity (PE = KE) vs. actual velocity (d/t)