Pendulums

Pre-Assessment

1. What is your personal experience with swinging on anything like a trapeze?
swinging on a swing
swinging on a trapeze bar (on kid's playlets) by your knees
swinging on a rope out over a lake/river

2. What applications to "real life" do swinging objects have?
pendulums on clocks, metronomes
swings

3. What is your prediction about what will happen if 2 people are on one trapeze and only 1 is on the other and the second switches to the one?
The one who "gave away" a person will lose momentum? The new group of 2 will have more weight and swing "harder." ????

4. What understanding or ideas do you have about the science of back-and-forth swinging objects?
kinetic energy is the energy of movement
potential energy is the ...potential (the lull before it swings back)
potential energy= mass*gravity*height?

Predictions

I think lower weight will swing more times in 10 seconds than higher weight.
I think doubling the weight will half the frequency, but double the total length of time that the pendulum keeps swinging (if we didn't stop it after 10 seconds).

Experiment

COntrol: Length (15 cm), angle of starting swing (22.5 degrees), time (10 seconds)
Variable: # of Washers

1 washer: avg. of 12.25 swings
2 washers: avg. of 12.375 swings
3 washers: avg. of 12.25 swings
4 washers: avg. of 12.25 swings

Conclusion: Weight does not affect frequency of pendulum swings

Our Experiment

Control: Angle of starting swing (22.5 degrees), Time (10 seconds), No. of Washers (4)
Variable: Length of String

20 cm: avg. of 10.625 swings
25 cm: avg. of 10 swings

Conclusion: We predict that the longer the string, the fewer number of pendulum swings per 10 seconds. --> An inverse relationship to pendulum length and frequency of swing.