Why does a drawing pin have a sharp point?

to make the pressure large. A small area gives a high pressure from the same push.

How does the pressure in a lake change as a diver goes deeper?

It increases. There is more water above pressing down.

Which change increases the pressure a person puts on the ground?

standing on one foot. The same weight on a smaller area gives more pressure.

1 N/m². Pressure is force per unit area.

Two liquids are at the same depth. Liquid X is denser than liquid Y. Which statement is correct?

The pressure in X is greater. Pressure in a liquid is density × g × depth.

Pressure · Edexcel IGCSE Physics 4PH1 revision

In plain words

Pressure is how concentrated a force is. The same push on a small area gives a big pressure: a drawing pin goes into the wall, your thumb doesn't. In a liquid the pressure rises the deeper you go, because there's more liquid above pressing down.

Three things to know

Pressure = force ÷ area (p = F/A). Its unit is the pascal: 1 Pa = 1 N/m².
The same force gives more pressure on a smaller area: that is why a knife is sharp and snowshoes are wide.
In a liquid, pressure increases with depth and with density: change in pressure = density × g × depth (Δp = ρgΔh).

Worked example

A box weighing 600 N rests on a base of area 0.5 m². Find the pressure on the floor.

Pressure = force ÷ area.
= 600 ÷ 0.5 = 1200 Pa.

Tips and tricks

1 Pa is 1 N/m². If the area is in cm², either change it to m² (divide by 10 000) or give the answer in N/cm².
In a liquid, pressure depends on the depth and the density, not on the shape of the container.

6 questions, about 2 minutes.

It lands in your notebook with its questions as flashcards.

Pressure: 6 questions and answers

These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.

A force of 100 N acts on an area of 2 m². What is the pressure?
- 0.02 Pa
- 50 Pa (the answer)
- 102 Pa
- 200 Pa
p = F ÷ A = 100 ÷ 2.
Why does a drawing pin have a sharp point?
- to reduce the force needed
- to make the pressure large (the answer)
- to make the pressure small
- to increase the area
A small area gives a high pressure from the same push.
How does the pressure in a lake change as a diver goes deeper?
- It increases. (the answer)
- It decreases.
- It stays the same.
- It increases, then decreases.
There is more water above pressing down.
Which change increases the pressure a person puts on the ground?
- lying down
- wearing skis
- standing on one foot (the answer)
- wearing snowshoes
The same weight on a smaller area gives more pressure.
What is 1 pascal?
- 1 N
- 1 N m
- 1 N/m² (the answer)
- 1 kg/m³
Pressure is force per unit area.
Two liquids are at the same depth. Liquid X is denser than liquid Y. Which statement is correct?
- The pressure in X is greater. (the answer)
- The pressure in Y is greater.
- The pressures are equal.
- Pressure does not depend on density.
Pressure in a liquid is density × g × depth.

6 questions

Tap an answer and you’ll see straight away whether it’s right, and why.

Worksheet

4 questions, 10 marks. Write your answers on paper, then check them.

Pressure

Edexcel International GCSE Physics 4PH1 · 10 marks · papermunch.org

Name ______________________________ Date ______________

A box of weight 600 N rests on a base of area 0.50 m². Calculate the pressure on the floor.[2]
Show answerHide answer
1200 Pa. 600 ÷ 0.50.
I got this one
The pressure under a foot of area 0.020 m² is 30 000 Pa. Calculate the force the foot exerts.[3]
Show answerHide answer
600 N. F = pA = 30 000 × 0.020.
I got this one
Calculate the pressure due to 5.0 m of water. Density of water = 1000 kg/m³, g = 9.8 N/kg.[3]
Show answerHide answer
49 000 Pa. 1000 × 9.8 × 5.0.
I got this one
Explain why a dam wall is built thicker at the bottom than at the top.[2]
Show answerHide answer
Water pressure increases with depth, so the force on the wall is greatest at the bottom.
I got this one

Answers: Pressure

1. 1200 Pa. 600 ÷ 0.50.
2. 600 N. F = pA = 30 000 × 0.020.
3. 49 000 Pa. 1000 × 9.8 × 5.0.
4. Water pressure increases with depth, so the force on the wall is greatest at the bottom.