Physics Liquid and Atmospheric Pressure Worksheet
1. A building is 512 m high. What must be the minimum water pressure in a pipe at ground level in
order to get water up to a restaurant on the top floor? (Density of water - 1000 kg m-3,
acceleration due to gravity = 10 m s-2)
2. A height of 0.81m of a column of turpentine exerts the same amount of pressure as a heavy box
of weight of 68,040N. The base area of the box is 10 m2. What is the density of turpentine?
3. Some air is trapped in a mercury barometer as shown in the diagram. If the atmospheric pressure
is 75 cm Hg, what is the pressure exerted by the trapped air (in cm Hg)?
4. The floor on a dance hall can take a pressure of 3.5 MPa before getting damaged. A lady of mass
60 kg wears high heeled shoes. What is the smallest area of the sole of a heel she could wear
such that it won’t permanently damage the floor?
5. A hydraulic lift is used in a garage to raise a vehicle to enable the underside to be repaired. The
maximum pressure of the hydraulic lift is 1.2 MPa. The area of each of the four legs of the lift is
9.0 x 10-3 m2. Calculate the maximum safe load the lift can raise if the lift platform weighs 1.5 x
104 N.
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6. The diagrams (a) and (b) show an open-ended and a closed tube manometer connected (at different times)
to the same gas cylinder. The mercury barometer reads 760 mm atmospheric pressure. Assume that there is
no loss in the pressure from the gas cylinder. What is the height x of the mercury in the diagram (b)?
7. The pressure exerted by a water jet of area 5 mm2 is 20 MPa (20 000 000 Pa). What is the force exerted on
the ground if the jet of water strikes the ground vertically?
8. a) If the diameter of the first piston is 23cm, calculate the surface area, and the resultant
pressure that a force of 12.5 N creates.
b) If the same piston is connected up by hydraulics to a second piston, how large does the
surface area have to be to lift a car of 20,000N?
9. Calculate the pressure exerted by a paving stone of density 2500 kg m-3 and of dimensions 0.80 m
x 0.80 m x 0.05 m when the stone rests flat on a horizontal surface.
10. The mean value of atmospheric pressure is 101 kPa. Calculate the force due to the atmosphere
on the panes of a window with dimensions 1.5 m x 0.8 m.
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