Friction is all around us

Look at the photographs and explain in each case where friction comes into play. Say whether the frictional forces are a nuisance or useful. The first one is done for you as an example.

Rock climbing

Friction between:a) the hands of the rock climber and the rope: usefulb) the shoes of the rock climber and the rock face: useful

Pushing a car Motorcycle racing

Athletes racing Pushing a supermarket trolley

Answers to questions:Rock climbingFriction between :

a) The hands of the rock climber and the rope – useful.b) The shoes of the rock climber and the rock face – useful.

Pushing a carFriction between

a) The feet of the people pushing against the ground – useful.b) The car tyres and the surface they are in contact with – nuisance.

Motorcycle racingFriction between :

a) The motorcycle seat and the motorcyclist – useful.b) The tyres and the road – useful.c) The air and the machine and its rider – nuisance.

AthletesFriction between :a) The feet and the track surface – useful.b) Air and the runners – nuisance.

Pushing a supermarket trolleyFriction between :

a) The trolley wheels and the floor – nuisance.b) The feet of the person pushing the trolley and the floor – useful.c) The hands and the trolley handle - useful.