Answer
(a) $0.95J$
(b) $0.95J$
(c) $41^{\circ}$
Work Step by Step
(a) We can find the required kinetic energy as follows:
$K.E_B=\frac{1}{2}mv_B^2$
We plug in the known values to obtain:
$K.E_B=\frac{1}{2}(0.33)(2.4)^2$
$K.E_B=0.95J$
(b) We know that if the potential energy at point B is zero, the Bob's kinetic energy will be converted to potential energy when the bob reaches the maximum height. Thus, the required change in potential energy between point B and the other point where the Bob comes to rest is $0.95J.$
(c) We can find the required angle as
$\theta_{max}=cos^{-1}(1-\frac{\Delta U}{mgL})$
We plug in the known values to obtain:
$\theta_{max}=cos^{-1}(1-\frac{0.95}{(0.33)(9.81)(1.2)})$
$\theta_{max}=41^{\circ}$
