PHYSICS · Multi-part · CBSE · Physics · System of Particles and Rotational Motion · System of Particles and Rotational Motion
Problem
A playground seesaw is a uniform plank 4.0m long, pivoted at its centre O. A child applies a 200N downward force at the right-hand end such that the force makes an angle of 30∘ with the horizontal plane of the plank.
(i) Determine the magnitude of the torque produced by the child about the pivot.
(ii) The child now moves to a point 1.0m from the pivot while maintaining both the magnitude and direction of the force. Calculate the new torque and find the ratio of the new value to that obtained in part (i).
(iii) Returning to the original position at the end of the plank, the child doubles the magnitude of the force while keeping the same angle. Compare this torque with that in part (i), and explain why the change occurs.