Question

A boy of mass 50.7 kg is initially on a skateboard of mass 2.00 kg, moving at a speed of 10.4 m/s. The boy falls off the skateboard, and his center of mass moves forward at a speed of 11.1 m/s. Find the final velocity of the skateboard.

Answer 1

Use Conservation of Momentum. Find the momentum of both boy and skateboard before and after the fall.

Answer 2

could you show this because I not the one in the class my friend is and I'm just posting the question on here for him

Answer 3

Your friend should be here then. I can explain it to him in detail.

Answer 4

The equation for the conservation of momentum is this:

m_1*v_1i + m_2*v_2i = m_1*v_1f + m_2*v_2f

Where
m = mass
v = velocity
i = initial
f = final

Answer 5

Applied to your question:

(50.7)(10.4) + (2)(10.4) = (50.7)(11.1) + (2)v_2f
(527.28) + (20.8) = (562.77) + (2)v_2f
548.08 = 562.77 + (2)v_2f
-14.69 = (2)v_2f
-7.345 = v_2f

So the skateboard moves 7.345 m/s in the opposite direction.