Module 9 · Practice
Practice questions
Three difficulty levels.
Section A — Easy
State the equation linking speed, distance and time.
Calculate:
State the equation for pressure in a solid, with units.
What does a flat horizontal section of a distance–time graph mean?
State the equation for the moment of a force.
Section B — Medium
A car travels 144 km in 2 hours. Calculate its average speed in km/h and m/s. (Hint: 1 km = 1000 m, 1 h = 3600 s.)
An elephant weighs 40 000N and stands on four feet, each 0.05 m². Find the pressure each foot exerts on the ground.
Why does a sharp knife cut more easily than a blunt one, even with the same force?
A see-saw is balanced. A 25N child sits 1.6m from the pivot. A second child weighs 40N — how far from the pivot must they sit on the other side?
Explain, using ideas about particles, why a sealed bottle of fizzy drink builds pressure when warmed in the sun.
Section C — Hard
Sketch a distance–time graph for the following journey and describe each section:
0–10s: walks 20m at constant speed; 10–20s: stands still; 20–30s: runs 30m at constant speed; 30–40s: walks 10m back to where she stopped at 20s.
Explain why a dam wall is thicker at the bottom than at the top.
A spanner is 25 cm long. A force of 80N is applied at the end. Calculate the moment in Nm.
A door has its handle far from the hinge. Explain why it is much harder to open the door if you push close to the hinge.