Page 171 - Physics
P. 171
Pressure
total force on the submarine’s
outer hull? Use the density of
seawater 1 100 kg/m .
3
(b) Winds in the atmosphere
Liquid h blow from regions of high
atmospheric pressure towards
regions of low atmospheric
x
pressure. Would you expect
Trapped air the wind to blow from warm
regions to cooler ones or from
Curved
tube cooler to warmer areas? Explain
your answer.
Figure 7.45 12. In a hydraulic brake system, the
The difference between the liquid piston in the master cylinder has a
levels is h. At room temperature, h diametre of 2.0 cm and the piston in
is 0.57m. The density of the liquid the slave cylinder has a diametre of
is 1.4 × 10 kg/m or 14 000 kg/m . 3.5 cm. The brake pedal is pushed
3
4
3
The gravitational field strength down 10 cm with a force of 50 N.
g is 10 N/kg and the atmospheric How far do the brake shoes move
pressure is 1.0 × 10 Pa. Calculate and with what force do they press
5
the pressure of the trapped air. against the brake drum?
8. Why are dam walls constructed 13. Explain why it would not be practical
thicker at the bottom than at the top? to make a Fortin-type barometre
with water instead of mercury. Hint:
9. Explain why a diver at the bottom
of a dam experiences the greatest Compare the densities of water and
pressure mercury.
14. Both the aneroid barometre and the
10. A can holds water with a constant Fortin barometre are used to measure
depth of 0.5 m. The surface of the pressure. The working principles and
water is exposed to the atmosphere. mechanisms of these two objects
What is the pressure on the bottom differ. How can one distinguish
of the can? (g = 10 N/kg and atm. between the two?
pressure = 101.3 kPa).
15. If a passenger swallows their saliva
11. (a) A submarine has a surface area every 20 seconds during take-off,
of approximately 82 000 m . If and the take-off lasts for 2 minutes,
2
it is travelling at a depth of 0.3 how many times will they have
km in the ocean, what is the swallowed during take-off alone?
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Physics Form 1 Final.indd 165 16/10/2024 20:57
