Question

Two ice skaters stand face to face and push off and travel directly away from each other. The boy has a velocity of 5 m/s and he weighs 750N. The girl weighs 480 N. What is the girls velocity?

Answer 1

Given:

Weight 1 = 750N

Weight 2 = 480 N

V1 = velocity 1 = 5 m/s

First, calculate the masses of each one:

w = mg

g= 9.8 m/s

W1 = m1 g

750 = m1 (9.8)

m1= 750 /9.8 = 76.5 kg

m2 = 480/9.8 = 49 kg

Both momentums (p) add up to zero

p = mv

p1 + p2 = 0

m1v1 + m2v2 = 0

(76.5) (5 ) + (49)(v2) = 0

382.5 +49v2 = 0

382.5 = -49v2

382.5/-49 = v2

v2 = -7.8 m/s ( negative since velocity is in the opposite direction of the boy)