Every card in Forces and motion, Year 8: more practice
The whole deck, in order — so you can read it through before your child ever sees it.
- A 50 N force acts 0.4 m from a pivot. What is its moment in newton metres? (number only)
20
HintMoment = force × distance from the pivot.
Why50 × 0.4 = 20 N m.
- A boat is pushed forwards by a 20 N force while water pushes back with 12 N. What is the resultant force in newtons? (number only)
8
HintForces in opposite directions are subtracted.
Why20 − 12 = 8 N, in the forward direction.
- A sledge is pulled forward by 40 N and friction is 40 N backwards. It is moving. What happens to its speed?
It stays the same
HintWhat is the resultant force?
WhyThe resultant force is 0 N, so there is no change in motion: the sledge keeps moving at a steady speed in a straight line.
- A force of 600 N acts on an area of 0.03 m². What is the pressure in pascals? (number only)
20000
HintPressure = force ÷ area.
Why600 ÷ 0.03 = 20 000 Pa (20 000 N/m²).
- Is the pressure greater at the same depth in sea water or in fresh water?
Sea water
HintThe two liquids differ in density.
WhyPressure depends on depth and on the density of the liquid. Sea water is denser, so the pressure is greater at the same depth.
- Two points are at the same depth in a lake. How do the pressures there compare?
They are equal
HintWhat does the pressure in a liquid depend on?
WhyPressure in a liquid depends on depth, not on the direction or the width of the container above the point.
- What instrument measures atmospheric pressure?
A barometer
HintIts name includes the Greek word for weight.
WhyBarometers measure the pressure of the air, which changes with the weather and altitude.
- When you drink through a straw, what pushes the liquid up it?
Atmospheric pressure on the liquid in the glass
HintSucking removes air from the straw, so what pushes from outside?
WhySucking reduces the pressure in the straw, and the greater air pressure on the surface of the drink pushes the liquid up.
- A toy boat floats at rest and weighs 5 N. What is the upthrust on it in newtons? (number only)
5
HintThe forces must be balanced.
WhyA floating object is in equilibrium, so upthrust equals weight: 5 N.
- A steel bolt sinks but a steel ship floats. What is the key difference?
The ship's shape means its average density is less than water's
HintThink about all the space inside the hull.
WhyA ship is hollow and encloses a large volume of air, so its overall density is less than that of water.
1★ KS3-PHYS-FOR-0059
2★ KS3-PHYS-FOR-0060
3★ KS3-PHYS-FOR-0061
4★ KS3-PHYS-FOR-0062
5★ KS3-PHYS-FOR-0063
6★ KS3-PHYS-FOR-0064
7★ KS3-PHYS-FOR-0065
8★ KS3-PHYS-FOR-0066
9★ KS3-PHYS-FOR-0067
10★ KS3-PHYS-FOR-0068
Keep what you learn
Here, nothing is saved. In your child’s own sky every card is scheduled — it comes back just before they’d forget it — and the professor who wrote it is one tap away.