Simple mechanisms
Design & Technology · Key Stage 1 · The School
Levers
A LEVER turns around a fixed point. That point is called the PIVOT. A lever lets a small force move a big load. Scissors are levers. So is a see-saw. So is a wheelbarrow, and a spoon opening a tin. Move the pivot closer to the load and the lever gets easier to use. Move it further away and it gets harder.
Sliders and wheels
A SLIDER moves in a straight line along a track. Guides hold it in place, like a drawer in a cupboard. A WHEEL AND AXLE turns to move something along. The wheel turns, and the axle carries it. Both of these change how movement travels. Neither of them changes how much force there is.
Hinges and linkages
A HINGE lets one part swing while the other part stays still. A door has one. So does a book, and the lid of a box. A LINKAGE joins parts so that moving one moves another. Sometimes it moves in a different direction entirely. Pop-up books are made almost completely of levers and linkages. Open one slowly and watch the card arms push each other along.
Lift a heavy book straight up by 10 cm. It is hard, and it is a short distance. Now use a ruler as a lever, with a pencil under it as the pivot, close to the book. Press the far end of the ruler down by 30 cm. The book rises 10 cm. That was much easier. But you moved three times as far. Force went down by about the same amount that distance went up. The lever traded one for the other. It did not make anything out of nothing.