Forces affect the movement or shape of an object. Gravity and Air resistance are examples of forces. Forces can cause objects to move, and sometimes slow, stop or change the direction of an object's motion.

Gears, pulleys and leavers are simple mechanisms which allow a small force to be converted into a larger one. Gears are wheels with teeth. When gears are placed next to each other, their teeth slot together (see pictures).  

'We have learnt that objects that have bigger surfaces will fall slower than objects that have a small surface area. A pulley was used in the olden times to help lift heavy objects' Mustapha