1. A 4-kg skateboard moving at 8 m/s collides with another identical skateboard initially at rest. If the two skateboards stick together, what is their speed after the collision?

It is d, all the other ones say incorrect answer .

F= (mass)(acceleration) = mam = 0.25 kgvi = 16 m/st = 2 svf = 0 m/s (since it was put to stop)a=(vf-vi)/ta=(0-16)/2a = 8 m/s^2 (decelerating)f = ma = (0.25 kg)(8 m/s^2)f = 2 nhope this !