# Warm-Up Exercise for lecture 12

## Due 8:00 am, Tues, 8 Oct 2009

Physics 105, Fall 2009

Enter your 3-digit class identification number:

Enter the last 4 digits of your BYU ID:

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

Which has greater linear speed, a horse near the outside rail of a merry-go-round or a horse near the inside rail?
☐ outside horse
☐ inside horse
☐ both the same

Which has greater angular speed, a horse near the outside rail of a merry-go-round or a horse near the inside rail?
☐ outside horse
☐ inside horse
☐ both the same

A ladybug sits on the outer edge of a merry-go-round that is turning around counter-clockwise without speeding up or slowing down. In what direction is the friction force that sticks the ladybug to the merry-go-round?
☐ clockwise
☐ counter-clockwise
☐ inward
☐ outward

Ralph is confused about centripetal and centrifugal forces. When he is in a car which is turning to the left, he feels a force pushing him to the right. But the textbook says that the actual force is pushing him to the left. Can you explain this to him? What is he feeling during the turn?

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?