Answer
a) $\Sigma \tau=-2.14Nm$
b) clockwise, downward
c) increase
Work Step by Step
(a) We know that
$\Sigma \tau=(12.6N)(2.75\times 10^{-2}m)-[(1.20Kg)(9.81m/s^2)](0.17m)-(1.42N)(0.34m)$
$\implies \Sigma \tau=-2.14Nm$
(b) Since the net torque is negative (that is, in the clockwise direction), the forearm and the hand rotate downward.
(c) In the given scenario, the net torque increases because the distance of $F$ from the axis of rotation is greater.
