# Warm-Up Exercise for lecture 6

## Due 8:00 am, Thurs, 17 Sep 2009

Physics 105, Fall 2009

Enter your 3-digit class identification number:

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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

The force required to maintain an object at a constant speed in free space is equal to
☐ the mass of the object
☐ the weight of the object
☐ zero
☐ the force required to stop it
☐ none of the above

Two teams are having a tug-of-war, using a nylon rope with essentially no mass. Team A (on the left) is winning--both teams are accelerating to the left. What can you say about the tension in the rope?
☐ It is higher on the left than on the right.
☐ It is higher on the right than on the left.
☐ It is constant throughout the rope.

You slide a block of ice down a 45° ramp. There is no friction between the ice and the ramp. How will the acceleration of the ice block down the ramp compare to the normal acceleration of gravity, 9.8 m/s2? (compare magnitudes)
☐ ice block's acceleration will be greater than 9.8 m/s2
☐ less than
☐ still equal to

Ralph was thinking about the demo with the penny and feather falling in a vacuum. The penny and feather both fell at the same rate. He asked, "Does this mean that the force on the penny and the force on the feather are equal?" What would be a good answer (and explanation) to his question?

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?