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Bowling Ball Pendulum

This is demo is typically used to illustrate conservation of energy in freshman physics. In this demo, a pendulum is formed by a bowling ball of about 5kg attached to string about 2.5 m long, which is hung from the ceiling of the classroom. The idea is that students observe the conversion from gravitational potential to kinetic energy and vice versa. More importantly, the students should notice that at the end of a cycle the energy is back to where it was -perhaps a bit less due to some dissipation. A touch of drama is added if the ball is released from rest at a point close to the face of a student -make sure the student does not lean forward to meet the returning ball. Have the student sit on a chair about half a meter higher from the lowest point of the pendulum. Standing behind the student bring the bowling ball close to the student's nose. Release the ball while the rest of the group watch - just before releasing the ball ask some of spectators to be ready to call 911, to add to the suspense. It will be more engaging if you can make a movie and the project it on the screen for analysis.
ID: d0014
Set up time:
10 minutes for initial setup prior to class + 5 minutes to perform the demo.
Requires:
A hook on the classroom ceiling. Components.
Notes:
You may need assistance the first time you use this demo.Make sure that the ball starts from rest.You should do it first, before inviting a student to volunteer.If a student does volunteer, insist the he/she should not under any circumstance move or lean forward. In workman 101, it is best to remove the seat right next to the equilibrium point of the pendulum. You will need a 9/16'' wrench for this task.
Figures:
Documents:
Comments:

Table of Components

Qty. name location notes
1 Bowling ball with hook W106; Central Cabinets; U1-L1 (inside bowling bag)
1 string about 2.5m long.
1 Carabiner clip (spring hook) " to attached to the bowling ball hook.
1 Custom adapted carabiner clip " to attached to hook on ceilng.
Fishing line about 2.5m " to attach to the custom carabiner clip.
1 9/16" wrench " to remove chairs in the way of the pendulum in Workman 101.
1 Custom made pole W106; South Metal Shelves (top) to hook and unhook the string of the pendulum from ceiling hook.