[填空题]
Two billiard balls of e n2pvhdv6.. waqual mass move at right anw:y .l-:xm;/ sr4 b ryqw0txsggles and meet at the origin of an xy coordinate system. Ball A is moving upwas :;ywx.wtgmbyl -sr 0:4/xqrrd along the y axis at 2m/s and ball B is moving to the right along the x axis with speed 3.7m/s After the collision, assumed elastic, ball B is moving along the positive y axis (Fig. 7–37). What is the final direction of ball A and what are their two speeds? direction of ball A is v' = m/s v' = m/s