Pushes, pulls and friction
Physics · Key Stage 2 · The School
Every force is a push or a pull
Kicking a ball: push. Opening a drawer: pull. Forces start things moving, stop them, speed them up, slow them down, or change their direction. You cannot see a force — you see what it DOES.
Friction: the gripping force
When two surfaces rub, FRICTION pushes back against the sliding. Rough surfaces make more of it, smooth ones less. Friction is why shoes grip, why brakes work — and why ice, with almost none, sends you skating. It also turns motion into heat: rub your hands and feel it.
Gravity never lets go
Drop anything and it falls DOWN — gravity is the Earth pulling everything toward itself. It holds you on the ground, holds the Moon in its orbit, and gives things their weight. On the Moon, with weaker gravity, you would weigh about a sixth of what you do here.
Try to slide a shoe across a table by pushing it gently: it grips and barely moves. That is friction HELPING — it is why shoes work and why brakes stop a bike. Now put the shoe on a sheet of paper and push: it slides easily. Friction has been reduced. Finally, rub your hands together fast: they get warm, because friction turns movement into heat — which is why machines need oil.