A door can be opened by pushing it at different positions. Explain why pushing the door at a point far from the pivot produces a larger turning effect than pushing it with the same force at a point close to the pivot.

1. The turning effect of a force is called its moment, which is the product of the force and the perpendicular distance from the pivot to the line of action of the force.
2. When the door is pushed far from the pivot, this perpendicular distance is larger.
3. Because the force applied is the same, a larger perpendicular distance gives a larger moment, i.e. a greater turning effect.
4. Conversely, pushing close to the pivot gives a smaller perpendicular distance, so the moment and the turning effect are smaller for the same force.