Pn Haziah bt Awang Lah, Sekolah Sultan Alam Shah. 2007

3.2 UNDERSTANDING PRESSURE IN LIQUIDS

Characteristics of pressure in liquids.

1. Draw the jet of water.

2. Draw the water level in the container.

3. The hole in both containers are at the same height. Draw the jet of water and oil.

TEACHER’S SIGNATURE : …………………………44

Pressure in liquids is acting in all direction Pressure in liquids increases with depth

The object is floating in dead sea because the density of sea water is high.

It shows that the pressure is increased with density.

P = Pressure ( Pascal)ρ = density ( ) g = h = height (m)

P = hρg

It shows that depth affect the pressure in liquids

Shape and size do not influence the pressure

wateroil

Pn Haziah bt Awang Lah, Sekolah Sultan Alam Shah. 2007

Applications of pressure in liquids.

Give one example.

Solving problem

1. An air bubble is at a depth of 5 m below the surface of a lake . What is the pressure of water on the bubble if the density of the water is 1 000 kg m-3?

2. The figure shows a cylinder containing oil with a density of 800 kg m-3.

What is the pressure caused by the oil at point X?

3. The figure shows a high tin with a length of 100 cm is filled to the full with water.

If the pressure caused by the water at point P is 8000 Pa, What is the value of L? (Density of water = 1000 kg m - 3 )

4. A diver wears a watch which can withstand a pressure of up to four times the atmospheric pressure. What is the limit of depth that the diver can dive before his watch is damaged? ( Density = 1 gcm-3 , gravitational acceleration = 10 ms-2, atmospheric pressure = 1.0 x 105 Pa. )

5. A Water flow out from a hole at the side of a container which is fully filled with water. What will happen to the rate of flow of water if the container is closed tightly with a lid?

TEACHER’S SIGNATURE : …………………………45