Question

A uniform rod 4m long weighing 2kg rest on smooth supports at its ends. If weights of 1kg and 5kg are hung at distances of 1m and 3m from one end, find the thrusts on the support.

Answer 1

Answer:

From one end the torques are:

F1 * 4 = (2 * 2 + 1 * 1 + 5 * 3) g = 20 g       F1 = 5 g

Balancing torques from the other end:

F2 * 4 = ( 2 * 2 + 1 * 3 + 5 * 1) g = 12 g       F2 = 3 g

As a check the total vertical forces must balance:

(2 + 1 + 5) g = F1 + F2 = 8 g