[填空题]
A 0.280-kg croquet ball makes v* ,q6xy)msyv an elsd3)tu2:6d(2agbqqa5 fgh zkt95abp)t 1neu astic head-on collision with a second ball initially at rest. The second ball moves off with half the hk geatn63 q(g2d25)uufq db1ba95t zat s):poriginal speed of the first ball.
(a) What is the mass of the second ball? kg
(b) What fraction of the original kinetic energy $(\Delta\mathrm{kE/KE})$ gets transferred to the second ball?
