Dan is gliding on his skateboard at 30 ms He suddenly jumps

Dan is gliding on his skateboard at 3.0 m/s. He suddenly jumps backward off the skateboard, kicking the skateboard forward at 6.0 m/s (as measured by an observer on the ground). Dan\'s mass is 70 kg and the skateboard\'s mass is 5.0 kg. How fast is Dan going as his feet hit the ground? Express your answer using two significant figures.

Solution

from the law of conservation of momentum:

m₁v₁+ m₂v₂ = m₁v_1f +m₂v_2f

(70)(3) +(5)(3) = (70)(v) + (5)(6)

therefore, the velocity is, v= 2.8 m/s