Moments, levers and gears
A force or a system of forces may cause an object to rotate.
Students should be able to describe examples in which forces cause rotation.
The turning effect of a force is called the moment of the force. The size of the moment is defined by the equation:
moment of a force, M, in newton-metres, Nm force, F, in newtons, N distance, d, is the perpendicular distance from the pivot to the line of action of the force, in metres, m.
If an object is balanced, the total clockwise moment about a pivot equals the total anticlockwise moment about that pivot.
Students should be able to calculate the size of a force, or its distance from a pivot, acting on an object that is balanced.
A simple lever and a simple gear system can both be used to transmit the rotational effects of forces.
Students should be able to explain how levers and gears transmit the rotational effects of forces.