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FORMULA

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Pressure in liquid

acts in all directionsincreases with depthis independent of the size and shapeof the container.

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Relationship between depth andpressure in liquid

Liquid exert pressure due to their own weight.Example: There are 3 hole of differentdepths. Hole P is the highest while, hole Qand S follows.Water streams come out through every holeon the tin. This means that the water in thetins exerts pressure in all directions. In all theholes, water stream that comes out of the

lowest hole reaches the farthest. This showsthat the pressure exerted but a liquidincreases with depth. This stream that comeout of hole P is the lowest.

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HOLE P

HOLE Q

HOLE R

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Relationship of density andpressure in liquid

Pressure in a liquid can be measured by using amanometer.Figure below shows the manometer funnel placed atthe same depths in 3 beakers, each containing water,salt solution and alcohol respectively.

The pressure is the highest in salt solution and thelowest in alcohol. As salt solution has the highest density while alcoholhas the lowest, we can say that pressure is dependenton the density of the liquid.The higher the density of a liquid, the higher thepressure.This is because a liquid with a higher density has ahigher mass in a unit volume and thus exerts a higher pressure due to its weight.

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Public Water Supply System

Dams and reservoir are placed inhigher location, so that the water willhave sufficient pressure to flow to

consumers at lower levels.The pressure between the flowingwater and our water tank is called

water pressure.

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Transfer of saline solution topatients

Intravenous infusion is when salinesolution are infused into your bloodstream.

Saline bags/bottles are placed at anelevated position in order for there tobe enough pressure to flow into our

veins.

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QUESTIONS TIME!! :D1. A boy swims at a depth of 1.5m in a swimming pool.Calculate the pressure of water experienced by the boy

while swimming at that depth.[density of water = 1x106^3 kg m^-3]

2. The density of oil is 900 kg m^-3. the pressure exerted bythe oil at a height of 30 cm is?

3. When the height of liquid x is 10 cm and the height of liquidy is 20cm, the distance of the liquid spurt for the two liquidsare equal.[density of liquid x = 1.5g cm^-3]

4. the pressure of sea water at the sea bed is 1.1x10^8 N m^-2. Calculate the depth of the sea. [density of water =1.02x10^3 kg m^-3]

5. If the height of P from the bottom of a beaker is 8cm andthe height of Q from the bottom of the same beaker is10cm, at which point is there more pressure?

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ANSWERS!! :D(prepared by Pak Cheng Theng)1. p = 1000(1.5)(10)

p = 15000Pa2. p = hg

p = 900(0.3)(10)p = 2700 N m^-2

3. 10(10) = 10(20) liquid x = 1.5g cm^-3liquid y = 1.5 /2= 0.75g cm^-3

4. 1.1 x 10^8 = (1.02 x 10^3)(h)(10)= 1.02 x 10^4(h)5. ans : P

because the depth of P is deeper.