[填空题]
A ball on the end of a string is revolved at a uniform rate in a ve*gf 1sy lkrw50rticalsu +q)f ssmdd g9() 5mbvupo.5 circle of radius 72.0 cm , as shown in Fig. 5-33. If its speed is u5d+dom5g qvsm) )f9s s( .pbu4.00 $\mathrm{~m} / \mathrm{s}$ 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.
