wunder beta⚙️ Pressure, Moments, and Hooke's Law
Three big ideas about forces: how pressure spreads a force over an area, how moments make things turn, and how Hooke's law links stretch to force.
What you’ll learn
- Pressure: Force Spread OutUnderstand that pressure = force ÷ area, and that spreading a force over a larger area lowers the pressure.Pressure measures how concentrated a force is, calculated as force divided by area and measured in pascals. The same force gives high pressure over a small area, like a sharp drawing pin or a stiletto heel, and low pressure over a large area, like snowshoes or a camel's broad foot.
- Turning Forces: MomentsCalculate the moment of a force as force × perpendicular distance, and apply the balancing rule for moments.A moment is the turning effect of a force, found by multiplying the force by its perpendicular distance from the pivot, measured in newton metres. Acting further from the pivot gives a larger moment, which is why long spanners and far-out door handles work well. An object balances when the clockwise moment equals the anticlockwise moment.
- Stretching: Hooke's LawState Hooke's law: extension is directly proportional to the force applied, up to the limit of proportionality.Hooke's law says a spring's extension is directly proportional to the stretching force: double the force and the extension doubles. This holds only up to the limit of proportionality, beyond which the pattern breaks and the spring may not return to shape. Newton-meters use this predictable stretch to measure force.
Questions this course answers
How do you calculate pressure?
Pressure is the force divided by the area it acts on, giving a result in pascals.
Why do wide snowshoes stop you sinking into deep snow?
Spreading the same weight over a bigger area lowers the pressure on the snow, so you do not sink.
A stiletto heel can dent a wooden floor because it has a very small contact area. This gives it a...
Squeezing a force into a tiny area produces a very high pressure, enough to dent wood.
How is the moment of a force calculated?
A moment is the force multiplied by the perpendicular distance from the pivot, measured in newton metres.
Why does a longer spanner loosen a stiff bolt more easily?
A longer spanner increases the distance from the pivot, so the same push produces a larger turning moment.
A seesaw stays balanced when...
A seesaw balances when the clockwise and anticlockwise moments are equal, so there is no net turning effect.
Grounded in trusted sources
- BBC Bitesize
- The Physics Classroom
- Britannica
Every Wunder lesson is built from real, reputable sources — never invented.
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