91Ó°ÊÓ

Rotational force, or torque, is what causes objects to rotate around a pivot point. Imagine pushing on a door to make it swing open. Your push is like a rotational force. If you push harder, the door swings faster, but where you push also matters.
The formula for torque is \(\tau = r \times F \) where \(\tau \) is torque, \(r \) is the distance from the axis of rotation (the pivot point), and \(F \) is the force applied. This means that both the amount of force and the distance from the pivot are important for generating torque.
Your push creates a force that travels to the pivot point, causing rotation. If you push far from the pivot, you get more torque. This is why it's easier to open a door when pushing at the edge rather than near the hinges.

A pivot point is the spot around which everything rotates. When opening a door, the hinges act as the pivot point. They don't move, but everything else does.
Consider a door as a lever. The hinge is the fulcrum or pivot point. When you push on the door, the force you apply travels through the door to the hinges. This makes the door rotate around the hinges, making them the key part in the door's rotation.
Think about a seesaw. The middle point is its pivot. The farther you sit from it, the easier it is to lift the other end. The same idea applies to the door: the farther you push from the hinge (pivot), the easier it is to make the door swing open.

The distance from the axis of rotation plays a major role in determining the force's effect on rotation. This distance is crucial in calculating torque.
If you apply the same force at different distances from the pivot point, the effect on rotation changes. The farther from the pivot you apply the force, the more torque you generate. This is why pushing a door near the edge is much more effective than pushing it near the hinges.
In our example, to make the door swing open quickly, you should apply the force at the point farthest from the hinges. This maximizes \(r \) in the formula \(\tau = r \times F \), thereby maximizing torque and causing the door to open faster and with less effort.