9.when you rub your hands together on a cold day, you use friction to transform
a. mechanical energy into thermal energy.
b. thermal energy into nuclear energy.
c. nuclear energy into electrical energy.
d. electrical energy into electromagnetic energy.

What is the radius of the circular path ofa charged particle in a magnetic field?

22. the effect of threshold braking is to a cause skids. b. lock wheels. c. prevent locking of wheels. d. increase stopping distance.

A1-lb collar is attached to a spring and slides without friction along a circular rod in a vertical plane. the spring has an undeformed length of 5 in. and a constant k =25 lb/ft. knowing that the collar is released from being held at a determine, the speed of the collar and the normal force between the collar and the rod as the collar passes through b.