Question

4. When making calculations to show Σ τ = 0 what is the advantage of choosing the axis of rotation at the position of one of the forces? Explain.

Answer 1

Solution

By choosing so you can effectively avoid(that is make it zero) the contribution to torque due to that particular force. Hence there will be one component lesser in the final summation.

This is due to the fact that torque due to a force is defined as,

Where,

Thus by choosing axis of rotation to be at position of one of the forces, the position vector r of that force will be zero. Hence torque contribution due to that force about the chosen axis will be also zero.