Physics
Physics
Problem
A horizontal, lightweight rod 1.2 m long is hinged to a wall at its left end. A 35 N weight hangs from the right end. Determine the magnitude of the upward force that must be applied 0.30 m from the hinge to keep the rod in equilibrium.Intuitive explanation
This is a torque balance problem where you need to recognize that a rigid body in equilibrium has zero net rotational effect around any pivot point. The key insight is to choose the hinge as your pivot: the weight creates a clockwise torque trying to rotate the rod down, and the applied upward force must create an equal counterclockwise torque to stop it. Since torque depends on both force and distance from the pivot, a force closer to the hinge needs to be larger to produce the same rotational effect.
Intuitive explanation
This is a torque balance problem where you need to recognize that a rigid body in equilibrium has zero net rotational effect around any pivot point. The key insight is to choose the hinge as your pivot: the weight creates a clockwise torque trying to rotate the rod down, and the applied upward force must create an equal counterclockwise torque to stop it. Since torque depends on both force and distance from the pivot, a force closer to the hinge needs to be larger to produce the same rotational effect.