How does the focal length (f) of a convex lens compare with the focal length
of a concave lens?

A. Both are negative.
B. The focal length of the convex lens is positive, and that of the
concave lens is negative.
C. The focal length of the convex lens is negative, and that of the
concave lens is positive.
D. Both are positive.

The mass of a bowling ball is 10 kg and the mass of a ping pong ball is 0.015 kg. if the two objects are 5 meters apart, what is the gravitational force ?

Suppose a comet has an orbital period of 309.1 years around the sun. what is it’s average distance from the sun?

Which of the following situations is impossible? a) an object has velocity directed east and acceleration directed east. b) an object has zero velocity but non-zero acceleration. c) an object has constant non-zero velocity and changing acceleration. d) an object has velocity directed east and acceleration directed west. e) an object has constant non-zero acceleration and changing velocity.