Solution :
Given :
mass of the plank, m = 14 kg
length of the plank, l = 1.9 m
Distance between and the end at which is acting, = 0.49 m
Torque exerted by the weight of the plank is given by :
= -130 Nm
The torque exerted by is
= 0
Torque exerted by is
Since the system is in equilibrium, the zero rotational acceleration occurs when the net external torque on the system is zero, i.e.
Therefore, we get
= 265 N (approx)
We know that zero linear acceleration occurs when the net external force is zero on the system to achieve equilibrium, i.e.
= 265 - (14 x 9.8)
= 128 N (approx)