[填空题]
A ball on the end of a)7x5k7:ikwevzoc* m o string u0 18kex -o*gvs5 x*chs4 owptis revolved at a uniform rate in a vertical circle of radius 72.0 cm , as shown in Fig. 5-335ot v whos1p*xxe8s - kguc4*0. If its speed is 4.00 $\mathrm{~m} / \mathrm{s}$ and its mass is 0.300 kg , calculate the tension in the string when the ball is (a) at the top of its path
(b) at the bottom of its path.
