Question

A person standing still on a skateboard decides to jump off quickly. If the velocity of the person in one direction is 4 ft./s, what is the velocity of the skateboard in the other direction? The skateboard weighs 15 pounds and the person weighs 120 pounds

Answer 1

Answer:

$v_s=32\ ft.s^{-1}$

Explanation:

Given:

velocity of the person in one direction, $v_p=4\ ft.s^{-1}$

mass of skate board, $m_s=15\ lb$

mass fo the person, $m_p=120\ lb$

Here the case is of elastic collision:

so, the skate will move in the opposite direction.

$m_p.v_p=m_s.v_s$

$120\times 4=15\times v_s$

$v_s=32\ ft.s^{-1}$