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Questions on Pressure

Q6.

Karen wants to pump up her car tyre.

Her pump has a piston with an area of cross-section of 7 cm2. Karen pushes the handle down with a force of 175 N.

(a) What pressure does she exert on the air in the pump?

P = F/A

P = 175/7

P = 25 N/cm2

(2 marks)

(b) The air pressure in the tyre is 27 N/cm2.

What pressure would be needed in the pump in order to pump more air into the tyre?

Any one from:

      • greater than 27 N/cm2 (the unit is required for the mark)
      • greater than the pressure in the tyre
      • any answer greater than 27 N/cm2 (the unit is required for the mark)

(1 mark)

(c) Another of Karen's car tyres exerts a pressure of 30 N/cm2 on the road.

The area of the tyre in contact with the road is 95 cm2

What is the force exerted by the tyre on the road?

P = F/A

F = P x A

F = 30 x 95 = 2850 N

(3 marks)

Total 6 marks