Question

A light rigid rod of length $4m$ is connected rigidly with two identical particles each of mass $m=2kg$, the free end of the rod is smoothly pivoted at O. The rod is released from rest from its horizontal position at $t=0$.

The reaction offered by the pivot at t=0 (in N) is $10x$. Find the value of $x$.

Answer 1

Angular acceleration at the time release is zero, therefore no centripetal force.

Hence there would only be vertical reaction on pivot balancing the weight of the two masses along y-axis$=2g+2g=4g=40N$