Question

A particle is falling freely along line x = a. The torque on the particle due to gravity about origin when it crosses x axis is
1. mga
2. 2^(1÷2)mga
3.mga2^(1÷2)
4.zero
The answer is mga. Please explain

Answer 1

Answer:

you know the eqn of the torqe is t=r×f

so here r=a and the force f=mg which is weight force becoz particle is falling due to gravity so

put that in eqn of torqe you get the ans mga