[填空题]
A ball of mass m makes a head-on elastic collision1yge;(kb ; ecdk/ef(t with a second ball (at restm / 8fyivlzd-6zpdv ;v-da2g -) and rebounds in the opposite direction with a speed equal to one-fourth its original speed. What is the mass of t/ gm zvz 2;id6vy-d pd-8vfa-lhe second ball? $m_B$ = $m_A$(Round to two decimal places)
