Question

An 108.0 kg boy and a 61.1 kg girl, both wearing skates face each other at rest on a skating rink. The boy and girl push each other, sending her eastward with a speed of 3.09 m/s. Determine the final velocity of the boy. Neglect friction.

Answer 1

$m_bv_b+m_gv_g=0,$

$v_b=-\frac{m_g}{m_b}v_g=-\frac{61.1}{108}\cdot 3.09=-1.75\space m/s.$

Answer: 1.75 m/s westward.