Moments & Levers + Gears

What is the moment of a force?

The turning effect of a force about a pivot.

What is a pivot?

The point about which an object turns or rotates.

Why must perpendicular distance be used when considering moments?

The turning effect depends on the perpendicular distance from the pivot to the force's line of action.

How can the moment of a force be increased?

Increase the force or the perpendicular distance from the pivot.

Why are door handles placed far from the hinges?

A greater distance from the pivot produces a larger moment for the same force.

What is the principle of moments?

For an object in rotational equilibrium, total clockwise moment equals total anticlockwise moment.

What is the resultant moment of a balanced object?

Zero.

Why can a small force balance a much larger force?

The smaller force can act at a greater perpendicular distance from the pivot, producing an equal moment.

What is a lever?

A rigid object that rotates about a pivot and transmits the turning effect of a force.

How can a lever increase the effect of a force?

By allowing the force to act at a greater distance from the pivot, producing a larger moment.

What is a gear?

A toothed wheel that transmits rotational motion and turning effects.

How do two meshing gears rotate?

In opposite directions.

Why are gears useful?

They can change the direction, speed or turning effect of rotation.

How does a large gear driven by a smaller gear affect the output?

The larger gear rotates more slowly but can produce a greater turning effect (torque).

Why does increasing the turning effect not mean energy is created?

Energy is conserved; increasing torque generally involves reducing rotational speed.