[填空题]
A softball of mass 0n /i1x+q7wv-axdn*57v cvt lh )d)br+ mm7 - ,rj wwy8bejjam2.220 kg that is moving with a speed of 8.5m/s collides head-on and elastically with another ball initially at rest. Afterward the incoming softbal7r-djebjwa+ )y)m jr8mbw ,2ml bounces backward with a speed of 3.7m/s Calculate
(a) the velocity of the target ball after the collision m/s
(b) the mass of the target ball. kg
(Let A represent the moving softball, and let B represent the ball initially at rest.)