Dan is gliding on his skateboard at 2.00 m/s. He suddenly jumps backward off the skateboard, kicking the skateboard forward at 7.00 m/s (as measured...

Dan is gliding on his skateboard at 2.00 m/s. He suddenly jumps backward off the skateboard, kicking the skateboard forward at 7.00 m/s (as measured by an observer on the ground). Dan's mass is 50.0 kg and the skateboard's mass is 5.00 kg.