A concrete paving block rests on flat ground. The block exerts a force of 900 N on the ground through its base, which has an area of 300 cm^2. What pressure does the block exert on the ground?

Pressure: Question 1

Syllabus 1.8

Multiple choice Core 1 mark

A concrete paving block rests on flat ground. The block exerts a force of $900\text{ N}$ on the ground through its base, which has an area of $300\text{ cm}^2$ . What pressure does the block exert on the ground?

Show worked solution Hide worked solution

Step 1: Recall the pressure formula

Pressure is force spread over area:

$p = \frac{F}{A}$

Step 2: Convert the area into square metres

The formula needs the area in $\text{m}^2$ , but it is given in $\text{cm}^2$ . Since $1\text{ m} = 100\text{ cm}$ :

$1\text{ m}^2 = (100\text{ cm})^2 = 10\,000\text{ cm}^2$

So:

$300\text{ cm}^2 = \frac{300}{10\,000}\text{ m}^2 = 0.03\text{ m}^2$

Step 3: Substitute into the formula

$p = \frac{900\text{ N}}{0.03\text{ m}^2} = 30\,000\text{ Pa} = 3.0\times10^{4}\text{ Pa}$

Why the other options are wrong

Option	How it arises	Error
$3.0\text{ Pa}$	$900 \div 300$	Area never converted from $\text{cm}^2$ to $\text{m}^2$
$3.0\times10^{2}\text{ Pa}$	$900 \div 3$	Area converted using the wrong (linear) scale factor
$0.33\text{ Pa}$	$300 \div 900$	Formula inverted (area ÷ force)

Final answers

Pressure $= \boxed{3.0\times10^{4}\text{ Pa}}$ , option B