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Physics

INV

1. Using a balloon, find out how gas pressure changes when its volume and temperature
change. Explain the results.

2. Check how Pascal’s Law works for liquids, using a plastic bag. Explain why Pascal’s Law
does not work for solids.
textbooks nis edu kz
3. Check how the pressure of liquid changes with depth, using a plastic bottle. Explain
how you understood this.

ACT At what depth are the fish in Balkhash Lake, one of the deepest lakes in Kazakhstan,
if the water pressure is 150 kPa and the density of the water is 1020 kg/m ?
3
Given SI Solution

р = 150 kPa 150 000 Pa р = ρgh 150 000 Pa
h = ≈ 15 m
ρ = 1020 kg/m 3 p kg N
h = 1020 m 3 · 9.8 kg
g = 9.8 N/kg ρ ∙ g

h = ?
Answer: h = 15 m

OVER TO YOU!

1. Why is the pressure in the saltwater area of Balkhash Lake greater than the pressure
in the freshwater area, at the same depth?

2. An equal quantity of water is poured into three containers – a glass, a bottle and
a kettle. In which container does the water exert the greatest pressure on the
bottom? What about the least pressure? Explain your answers.
3. Why, during a flight, does a packet of crisps become inflated?

EXT When swimming under water at great depth, your ears begin to hurt, making you
want to swim back up to the surface. Why do you think this happens? Using the key
words from this unit, prepare a presentation about what happens to human beings when
immersed under water using different technical devices.

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