Again in a movie projector, where is the film positioned?

a. a little under one focal length behind the lens.
b. exactly one focal length behind the lens.
c. a little over one focal length behind the lens.

Which is not a characteristic of a heat pump? a. it is used in air conditioners. b. it uses a refrigerant. c. it requires no work. d. it reverses the normal flow of thermal energy.

Which of these questions might a character ask if the conflict is man versus self? a. which path should i take to better myself? b. which boulder will be too heavy for me to carry? c. which friend is going to ditch me today? d. all of the above

What happens when a rubber rod is rubbed with a piece of fur?