Brainlag PlusThe turning effect of a force, M = Fd, the principle of moments for a balanced beam, and how levers and gears multiply forces.
The turning effect of a force
A force can make an object turn about a pivot.
Its turning effect is its moment.
moment of a force = force × distance
M = F d
M in newton metres (N m), F in N, d in m: the perpendicular distance from the pivot to the line of the force. All three boards: recall.
- A 20 N push on a door, 0.75 m from the hinges
- M = 20 × 0.75
- M = 15 N m
Change cm to m for an answer in N m. A longer spanner gives the same moment with a smaller force.
The rest of this lesson and its 10 practice questions are in Plus.
Screen 1 of 4, free to read.
- 10 exam-style questions, marked as you go, each with a worked solution
- Anything you get wrong is saved to your flashcards