1. Which of the following is not an example of friction?

a. Air resistance. c. a desk at rest.

b. a ball rolling down a hill. d. getting warm by a campfire.

2. Which is an example of helpful friction?

a. getting a static shock c. sliding across a gym floor on your

b. wearing batting gloves d. All of the above

3. The gravitational force between two objects depends on masses of objects and

a. accelerations of objects. c. speeds of objects.

b. distance between objects. d. sizes of objects.

4. Which of the following objects exerts the largest gravitational force?

a. a 10 kg bowling ball c. a 0.2 kg feather

b. a 1kg book d. All are the same