physics
posted by tj .
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 skaterâ€™s mass.

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
your welcome 
Ok you guys are retarded and definitely do not know your PEMDAS. The correct answer is 48 kg...