Momentum Qs: Find Girl & Skateboard Velocity After Jump

[crosbykins]

Homework Statement

A girl of mass 48kg runs toward her sationary 2.0kg skateboard and jumps on. The horizontal velocity of the girl just before she makes contact with the skateboard is 4.0m/s to the right. Disregard the effects of friction.
a)Determine the velocity of the girl after she has landed on the skateboard.
b)The girl then travels at this speed for a short time before jumping off, still traveling at the same speed as the skateboard. What is the velocity of the skateboard after she jumps off.

Homework Equations

p0=pf
(m1)(v01) + (m2)(v01) = (m1)(vf1) + (m2)(vf2)

The Attempt at a Solution

ok for b:
48kg * 4.0m/s = 50kg(v2)----> is this ok to consider skateboard and girl one
v2 =3.84m/s

ok for c) since she jumps off and has the same velocity, that means the skateboard will also have the same velocity

 

[willem2]

48kg * 4.0m/s = 50kg(v2)----> is this ok to consider skateboard and girl one
v2 =3.84m/s

It's ok to to consider girl and skateboard as one if they have the same velocity, which
they have. The answer is correct

ok for c) since she jumps off and has the same velocity, that means the skateboard will also have the same velocity

[/QUOTE]
This is OK as well.