A 2.00 kg blob of Gak, moving at 4.0 m/s, strikes a motionless figure skater in the back and sticks. The skater, with the Gak on her back, glides off at 0.160 m/s. Calculate the skater’s mass.

2 answers

Neglect friction (because of the ice skates)and assume conservation of momentum. That results in the equation

2.00*4.0 = (M + 2.00)*0.160

Solve for M, which will be in units of kg
mvi + mvi(2) = mvf + mvf(2) all energy is conserved
2(4) = (m + 2).16 (the masses are now combined)
8 = .32m
m = 25 kg

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