CK-12-Physics - Intermediate

7.1. Momentum http://www.ck12.org

FIGURE 7.3

50-kg moving 3.0 m/s.

Check Your Understanding

What momentum do the football players inFigure7.2 andFigure7.3 have?

Answer:

plarge=mlargev→(100 kg)( 3 .0m/s) = 300

kg·m

s

psmall=msmallv→(50 kg)( 3 .0m/s) = 150

kg·m

s

As can be seen above, the SI unit of momentum iskgs·m. There is no special name for this unit.

Illustrative Example 7.1.1

The cat inFigure7.4 has a mass of 6.1-kg and the mouse inFigure7.5 has a mass of 0.074 kg. What velocity would
the mouse require in order to have the same momentum as the cat, if the cat walks with a velocity of 0.50 m/s?

FIGURE 7.4

A 6.1-kg cat.

Answer:

The cat’s momentum ispc= ( 6 .1 kg)( 0 .50 m/s) = 3. 05 kgs·m

The mouse’s momentum is :pm= ( 0 .74 kg)(vm)