# 4.5.5.1

4.5.5.1 Pressure in a fluid

4.5.5.1 Pressure in a fluid

## Content

A fluid can be either a liquid or a gas.

The pressure in fluids causes a force normal (at right angles) to any surface.

The pressure at the surface of a fluid can be calculated using the equation:pressure = force normal to a surface

area of that surface

p=F/A

pressure, p, in pascals, Pa force, F, in newtons, N

area, A, in metres squared, m2

WS 4.3 Use SI units (eg kg, g, mg; km, m, mm; kJ, J) and IUPAC chemical nomenclature unless inappropriate.

WS 4.4 -Use prefixes and powers of ten for orders of magnitude (eg tera, giga, mega, kilo, centi, milli, micro and nano).

WS 4.5 - Interconvert units.

WS 4.6 - Use an appropriate number of significant figures in calculation.

MS 3b Change the subject of an equation

MS 3c Substitute numerical values into algebraic equations using appropriate units for physical quantities

Resources

Video SpikeySkateboard.mp4

Force and area 5wBGIHIE2IiZzsdW.mp4

How deep the oceon is

Practicals

Demo:

• Balloon
• Nail / pin
• Bed of nails

### Safety

Sharp pins/nails careful of pushing balloon down on them

### Practical

Demo:

• Water bottle filled with water
• Pin

### Safety

None - things may get wet

Demo to look how pressure changes with depth