Question

Please help I've attempted this problem various ways and I can't seem to get the correct answer.

A 69.0 kg person throws a 0.0410 kg snowball forward with a ground speed of 35.0 m/s. A second person, with a mass of 60.0 kg, catches the snowball. Both people are on skates. The first person is initially moving forward with a speed of 2.00 m/s, and the second person is initially at rest. What are the velocities of the two people after the snowball is exchanged? Disregard the friction between the skates and the ice.

Answer 1

This is a conservation of momentum problem. You have to do it in two steps, since there are two unknowns.

V1i = first person's initial velocity = 2.00 m/s
V1f = first person's final velocity = ?
m = snowball mass = 0.041 kg
M1 = first person's mass = 69 kg
M2 = second person's mass = 60 kg
V2i = second person's initial velocity = 0
Vrf = second person's final velocity = ?
v = snowball ground speed in flight = 35 m/s

(M1+m)*V1i = M1*V1f + m*v
Vif = (69.041/69)*2.00 - (0.041/69)*35
= 2.001 - 0.021 = 1.98 m/s

For person no. 2, let the initial state be with the snowball flying, and the final state after it is caught.
m*v = (M2+m)*V2f

V2f = (0.041)*35/(60.041)
= 0.024 m/s