You may be very familiar with swinging pendulums and the variables that do and do not affect. In this design lab, you will learn about how a torsional (twisting) pendulum works.
Francisca Sondjaja
Torsional Pendulum Design Lab
Aim:
You may be very familiar with swinging pendulums and the variables that do and do not affect. In this design lab, you will learn about how a torsional (twisting) pendulum works.
Apparatus:
- Ring stand and clamps
- Rubber bands
- Ruler
- Stopwatch
- Hanging Mass
- Sticky tack
- Coins
- Anything else you might find in a normal physics classroom.
Design:
Design a procedure to test how a certain variable (of your choice) may affect a twisting. As always, this should design lab should include…..
- Defining the Problem and selecting variables:
- Controlling the Variables:
- Developing a method for collecting data:
Thus, step by step instructions and diagrams are helpful to the reader and highly recommended. Also include a hypothesis and a sketch graph of what you think will happen.
The above information was given to the student by the instructor. What follows immediately below is the student’s own work.
Problem: How does increasing the number of coins on the ruler affect the time it takes for the torsional pendulum to complete one period?
Hypothesis: As number of coins on the ruler increases, the time to complete one period will also increase. This is because it takes more force to move a heavier mass. Because the simple equation of circular motion is , the distance between coin and center of mass (radius) is kept constant, and the amount of initial force applied to the ruler (the number of twists and rubber bands) is kept as constant as possible throughout the lab, as mass increases, velocity must decrease; this will increase the time for each period. Also, since the equation for force above can be rearranged to , perhaps the rate of increase of period over mass will slow down as mass keeps increasing, such as pictured in the graph above (like a square root graph).
