A simple pendulum has a string of length 1.5m and a bob of mass 0.30kg. It is pulled aside so that the bob moves 4.0cm along the arc and is then released. Using the small-angle approximation, calculate the magnitude of the restoring torque about the pivot at the instant of release. (Take g=9.8ms−2.)
a) 0.078Nm
b) 0.176Nm
c) 0.12Nm
d) 0.059Nm