\begin{problem*}{6.21}
An object of mass $m=0.500\U{kg}$ is suspended from the ceiling of an
-accelertating truck as shown in Figure P6.21. Taking
+accelertating truck as shown in Figure~P6.21. Taking
$a=3.00\U{m/s$^2$}$, find \Part{a} the angle $\theta$ that the string
makes with the vertical and \Part{b} the tension $T$ in the string.
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