# Warm-Up Exercise for lecture 25

## Due 8:00 am, Tues, 1 Dec 09

Physics 105, Fall 2009

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Did you complete the reading assignment? (Typically this means at least 20-30 minutes looking over the assigned sections of the book.)
☐ yes ☐ no

Some object is moving back and forth in harmonic motion. Where is the acceleration of that object greatest?
☐ at the midpoint of the motion
☐ at the end points of the motion
☐ same value at every point

Consider a mass m hanging on a spring. We pull the mass downward and then release it so that it oscillates up and down. If we repeat this on the moon with the same mass and the same spring, the frequency of the oscillation will be:
☐ larger
☐ smaller
☐ the same

Two students play with an extra-long Slinky. The student on the left end sends waves to the other student by shaking her end back and forth. After the waves die down, both students take a step backwards and try it again. How will the speed of the waves now compare to the previous waves?
☐ They will be faster
☐ They will be slower
☐ They will go the same speed

Ralph is confused about pendulums. He read in the textbook that the period T of a pendulum depends on its length L and on the acceleration of gravity g,but does not depend on its mass. Ralph thinks that heavier pendulums should swing with a longer period. After all, if he puts a heavier weight on the end of the spring, it oscillates more slowly. Can you help Ralph understand this?

The comments in the next next two boxes go into a big, mostly anonymous text file that I skim through before the morning lecture, using the comments to help me plan class discussion. ("Mostly anonymous", because I can track down who made what comment, but it takes some effort on my part to do so.) Therefore, if you really want to make sure I see your question/comment and answer it individually, you should send it to me via email and not through this form.

Which part of today's assignment was particularly hard or confusing? What would you like to spend extra time on in class?