A Why Do Think the Clown Sank Into the Sand?

In this activity, you are going to calculate pressure, force and area using the pressure triangle.

Force in newtons (N) / Area in square metres (m2) / Pressure in newtons per square metre (N/m2)
40 / 20 / A
300 / 50 / B
100 / C / 5
D / 200 / 20
0.5 / 0.25 / E
F / 20 / 0.5
0.1 / 25 / G

Copy and complete the table, calculating values for A–G.

Louise went to see the circus. The clown on his stilts struggled to walk as he kept sinking into the sand.

a Why do think the clown sank into the sand?

b Suggest two ways he could stop himself sinking in the sand. Which one is the most practical?

c What is the pressure underneath the stilts if they have a combined area of 0.25 m2 and the weight of the clown and the stilts is 700 N?

The next day Louise went back to where the circus had been, on her way to the shops. She found it difficult to walk, even in her boots, as she kept sinking into the mud. Louise makes a pressure of 12 000 N/m2 on the mud and she has a weight of 600 N.

a What area do her boots cover?

b If she carries the shopping home the same way and the shopping weighs 100 N, what pressure does she make on the mud?

Pressure is measured in N/m2 or in pascals (Pa). 1 Pa = 1 N/m2.

a What is the pressure in pascals that Louise makes on the mud on the way to the shops?

b What is the pressure in pascals that she makes on the way home, with the shopping?

This worksheet may have been altered from the original on the CD-ROM.