Questions where students often pick the tempting wrong answer — make sure you know the right one:
If an object is moving at constant velocity in a straight line, what is the net force on it?✗ There must be a forward force on the object to keep it moving.✓ Zero — by Newton's first law, constant velocity requires zero net force.
What is the difference between mass and weight?✗ Mass and weight are the same thing, just expressed in different units.✓ Mass is the amount of matter (kg); weight is the gravitational force on that mass (N) and depends on g.
If air resistance is ignored, which falls faster: a heavy ball or a light ball dropped from the same height?✗ Heavier objects fall faster than lighter objects because gravity pulls more on them.✓ Both fall at the same rate because gravitational acceleration is independent of mass.
When you push a wall, what does Newton's third law say about the wall?✗ The wall only pushes back if your force is strong enough to make it react.✓ The wall exerts an equal and opposite force on you at the same instant.
A car is slowing down as it brakes. What is true about its acceleration?✗ It has no acceleration because it is not speeding up.✓ It is accelerating — acceleration is any change in velocity, here negative.
Practise Forces & Motion — free games
Test yourself with these quick revision games for this topic:
