# Physics for Life science

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You are on a skateboard of mass 5.00kg with a ball in hands (mass of the ball is 600kg). You throw the ball forward horizontally and find that you recoil back with 2.0m/s. What is the forward speed of the ball? (Use your own mass where needed).

• Physics for Life science -

Assume there is no friction and use conservation of total momentum.
M1 = skateboard mass
M3 = ball's mass
Vr = recoil velocity
Vb = ball velocity
(M1 + M2) Vr + M3 Vb = 0
Vr = -[M3/(M1 + M2)]*Vb
Plug in your numbers. Vr is negative because the recoil is in the opposite direction

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