How to show the difference between force and pressure guide for KS3 physics students

Key points

A force can be a push or a pull. When a force is exerted on an object it can change the object's speed, direction of movement or shape.
Pressure is a measure of how much force is acting upon an area.
Pressure can be calculated using the equation pressure = force ÷ area. Therefore, a force acting over a smaller area will create more pressure.

Watch the video to learn the difference between force and pressure.

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Try this experiment

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Click to see a step-by-step slideshow.
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YOU WILL NEED: Weighing scales, calculator, ruler, pen, trainer, stiletto shoe and a piece of paper.
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STEP 1: Use the scales to find your mass in kilograms.
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STEP 2: Stand on a sheet of paper and use a pen and a ruler to draw a rectangle around the trainer. Do the same with the stiletto heel.
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STEP 3: Measure the sides of each rectangle and calculate their area. Finally calculate pressure.
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STEP 4: Put on the stiletto and stand on the grass. Do the same with the trainer.
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STEP 5: Observe the difference in pressure, by looking at the two footprints produced. The stiletto creates the biggest pressure, so it has made a hole.

How do we measure pressure?

Mass is a measure of how much matter there is. Gravitational force is the pull of the Earth's gravity on that mass. Each kg of mass is pulled down by the Earth with a force of 10 N.

Everything has a mass (kg). To convert this to force (N) on Earth, we multiply the mass by 10.

We can then calculate pressure using: pressure = force ÷ area.

If you stand on one foot (rather than both feet), the pressure exerted would be twice as great because it is spread over a smaller area. Similarly, a stiletto heel creates far more pressure than a normal shoe.

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