Question

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

Answer 1

Answer:

b. doubled

Explanation:

The momentum of an object is given by

$p=mv$

where

m is the object's mass

v is its velocity

We see that the momentum is directly proportional to mass. Therefore if the speed of the object is unchanged, but the mass is doubled: m' = 2m, the new momentum will be

$p'=m' v=(2m v)=2 (mv) = 2 p$

so the momentum is doubled.