A freight train rolls along a track with considerable momentum. If it rolls at the same speed but has twice as much mass, its momentum is (a) zero. (b) doubled. (c) quadrupled. (d) unchanged. When you...

A freight train rolls along a track with considerable momentum. If it rolls at the same speed but has twice as much mass, its momentum is

(a) zero.

(b) doubled.

(c) quadrupled.

(d) unchanged.

When you are in the way of a fast-moving object and can’t escape, you will suffer a smaller force if the collision time is

(a) long.

(b) short.

(c) The force is the same either way