Forces and Friction

• Forces are a push or pull.

• Forces usually work in pairs.

• Forces can be balanced or unbalanced.

• Two equal size forces acting in opposite direction on an object are called balanced forces.

• Two different size forces acting on an object are called unbalanced forces.

• Forces are measured by a device called force meter.

• The unit of force is newton.

• Friction is a force that works in opposite direction to movement.

• Friction slows down the speed of moving objects.

• Friction also produces heat.

• Rough surface produces more friction.

• We use oil to reduce friction between moving parts of a car engine.

• When we walk, friction prevents our feet from sliding all over the place.

• Different types of surfaces create different amounts of friction.

• There are four types of friction: static, fluid, sliding and rolling.