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Questions on Pressure

Q9. Alison has a car. The part of each tyre in contact with the road is flattened. This is shown in the diagram.

(a) When Alison gets into the car, the force on each tyre increases.

What happens to the area of tyre in contact with the road?

It increases

An increased force will increase the pressure on the tyre - flattening in more.

(1 mark)

(b) There is a leak of air from one of the tyres, and the air pressure in the tyre falls.

What happens to the area of the tyre in contact with the road?

It increases

A decrease in pressure means the the value of dividing the force (which stays the same) by the contact area must decrease - increasing that contact area will do that!

(1 mark)

(c) The weight of the car is 8400 N. Each tyre supports a weight of 2100 N.

The pressure exerted by each tyre on the road is 20 N/cm2.

Calculate the area of each tyre in contact with the road.

P = F/A

A = F/P

A = 2100/20

A = 105 cm2

(3 marks)

 

Maximum 5 marks