Edexcel IGCSE Physics 5.5 pressure equation

Practise pressure-equation questions by calculating pressure or force, converting weight where needed and explaining contact-area effects.

[Maximum number: 4]

A student investigates how much pressure she exerts on the ground when she is standing up.

(a)

The student measures the area of one of her feet when it is in contact with the ground. She draws around her foot on a piece of squared paper.

Figure for Question (a) — Edexcel IGCSE Physics

[ 4 ]

(i)

State the formula linking pressure, force and area.

[ 1 ]

pressure = force / area;

Notes: allow standard symbols
and rearrangements e.g.
$\mathrm{p}=\mathrm{F} / \mathrm{A}$

(ii)

The weight of the student is 520 N.

Calculate the pressure the student exerts on the ground when she is standing on both feet.

Give the unit.

pressure = ............ unit ............

[ 3 ]

Marking points:
- dimensionally correct substitution
- evidence of doubling area or halving pressure to account for both feet
- evaluation with matching unit

Example:
$\text{pressure}=\frac{520}{156}$ $\text{area}=156\times2$ $\text{pressure}=\frac{520}{156\times2}=1.7\ \mathrm{N\,cm^{-2}}$

Accept:
- ECF from 4(b)(i)
- $\mathrm{N\,cm^{-2}}$ , $\mathrm{N\,m^{-2}}$ , or $\mathrm{Pa}$ if no marks are awarded for the calculation
- $1.5\text{--}1.8\ \mathrm{N\,cm^{-2}}$
- $15000\text{--}18000\ \mathrm{N\,m^{-2}}$

Marking guidance:
- Allow 1 mark if a valid unit for pressure is given.

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5.5 Pressure equation question 1

Question (a)

Question (i)

Question (ii)