6.11Chapter 6: Forces, Motion and Pressure

Levers — Alhussan Physics - Stage 8 Revision Notes & Topical Questions

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📚 Alhussan Physics - Stage 8 Hub / Topical Revision

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Lesson summary

Physics 6.11 Levers — Pivots, Effort, Load and Force Multipliers — Alhussan International Academy — Physics (Stages 7–9) notes: Describe what a lever is and how levers act as force or distance multipliers.Turning effect — Forces can make objects turn as well as change their motio…

Levers in history
Pivot (fulcrum)
Turning force
Wheelbarrow
Balance of moments
Mechanical advantage

Section 1 of 7Turning forces

1Turning effect

Forces can make objects turn as well as change their motion.
Closing a door, using a wheelbarrow and sitting on a see-saw all apply turning forces.

2Levers in history

The ancient Egyptians used levers to lift huge blocks of stone onto rollers when building the pyramids.

Section 2 of 7Parts of a lever

Parts of a lever

Lever

Lever a bar that can turn when you exert a force on it.

Effort

Effort the force that you exert on the bar.

Load

Load the weight of the object that you lift, the force the lever applies to the load.

Pivot (fulcrum)

Pivot (fulcrum) the point about which the bar rotates.

Section 3 of 7How a lever works

Turning force

Pushing down on one end produces a turning force that makes the other end move up.

Force multiplier

The distance from the effort to the pivot is bigger than the distance from the load to the pivot.
A small effort can balance or move a much bigger load.
The effort moves through a greater distance than the load.

Energy

A lever does not give free energy: ignoring friction, the work done by the effort equals the work done on the load.

Section 4 of 7Force multipliers and distance multipliers

Type	Effort compared with load	Distance moved by effort	Examples
Force multiplier	Smaller than load	Greater than load	Crowbar, wheelbarrow, spanner, hammer removing a nail
Distance multiplier	Larger than load	Smaller than load	Tongs, tweezers, fishing rod

Wheelbarrow

The load is between the effort and the pivot (the wheel), so a small lift force supports a large weight.

Tongs

A small movement of the fingers moves the ends of the tongs much further, but with a smaller force.

Section 5 of 7Calculating with levers

Balance of moments

Effort × effort distance = load × load distance, both measured from the pivot.

Mechanical advantage

Mechanical advantage load ÷ effort, which shows how many times the force is multiplied.

Not always straight

Levers are not always straight bars.

Section 6 of 7Key terms

Term	Meaning
Lever	A bar that turns about a pivot when a force is applied.
Effort	The force applied to a lever.
Load	The weight or force the lever moves or overcomes.
Pivot (fulcrum)	The fixed point about which a lever turns.
Force multiplier	A lever that gives a bigger force on the load than the effort.
Distance multiplier	A lever that moves the load further than the effort moves.