Pressure in Fluids

Q. Define force and pressure.

Q. Why it is easier to swim in sea water than in fresh water?

1. Sea water is more dense than fresh water.
2. Fresh water is more dense than sea water.
3. Sea water exerts less upthrust.
4. Sea water has waves.

Q.

Give any one application of liquid pressure.

Q.

(a) How does the pressure of a liquid depend on its depth ? Draw a labelled diagram to show that pressure of a liquid (say, water) depends on its depth.

(b) Explain why, the walls of a dam are thicker near the bottom than at the top.

Q. Four plastic bottles of different shapes and sizes are joined together as shown in the figure. Water is poured in the bottle kept at the rightmost end.
Discuss whether the water level in the bottle in which water is poured will rise first or the water level in all the bottles will rise simultaneously. [2 marks]

Q.

Why do the shape and size of a balloon change, when filled with air or water?

Q.

The pressure at a point in a liquid is depends on:

1. height of the liquid column

2. mass of liquid

3. volume of liquid

4. area

Q.

Explain why a balloon bursts when too much air is blown into it?

Q.

Can a liquid exert pressure upwards ?

Q.

Can a liquid exert pressure sideways ?

Q.

Where is the pressure greater, 10 m below the surface of the sea or 20 m below the surface of sea?

Q.

Why does water evaporate before its boiling point?

Q.

What conclusion do you get from the observation that a fountain of water is created at the leaking joint of pipes of the main water supply line ?

Q.

Give an example of a hydrostatic pressure gradient that is negative.

Q. For which of the following vessels containing water in them is the pressure maximum at the bottom?

1. 
2. 
3. 
4. 

Q.

Explain why water comes out more slowly from an upstairs tap than from a similar tap downstairs.

Q.

When you punch holes in a bottle filled with water , it starts leaking but once you cap it , it stops leaking. Why is that?

Q.

Write true or false for each statement :

(a) The S. I. unit of force if kgf.

(b) A force always produces both the linear and turning motions.

(c) Moment of force = force $\times$ perpendicular distance of force from the pivoted point.

(d) Less force is needed when applied at a farther distance from the pivoted point.

(e) For a given thrust, the pressure is more on a surface of a large area.

(g) A man exerts the same pressure on the ground whether he is standing or he is lying.

(h) It is easier to hammer a blunt nail into a piece of wood than a sharply pointed nail.

(i) The S. I . unit of pressure is Pascal.

(j) Water in a lake exerts pressure only at its bottom.

(k) A liquid exerts pressure in all directions.

(l) Gases exert pressure in all directions.

(m) The atmospheric pressure is nearly ${10}^5$ Pa.

(n) Higher we go, greater is the air pressure.

Q.

The density of seawater is $1024kg/m^3$. The pressure at a depth of $5m$ below the surface of the sea is___ $N/m^2$

Q.

Pressure exerted by a liquid on the wall of its container is called_______

Q.

Some mustard oil is kept in a beaker. It will exert pressure:
(a)downwards only (b) sideways only (c) upwards only (d) in all directions

Q. What is the relation between liquid pressure and depth?

Q. How can fluid exert pressure?

Q.

Describe an experiment to show that liquid pressure at a given depth is same in all directions.

Q.

Two identical cubes A and B are placed in a tank containing a liquid as shown below. Choose the correct statement regarding pressures exerted on them.

1. The pressure experienced by cube A is more.

2. The pressure experienced by cube B is more.

3. The pressure experienced by cubes A and B are equal.

4. We need to know density of the liquid to compare the pressures experienced by cubes A and B.

Q. If liquid of density p is filled in an open cylindrical container to height h. Find the pressure at bottom?

Q. Write an expression for the pressure at a point inside a liquid. Explain the meaning of the symbols used.

Q.

One student says that water exerts pressure on the bottom of the bucket but another student says that water exerts pressure on the sides of the bucket. What would you like to say ?

Q.

Given that both liquid A and liquid B exert the same amount of pressure, what would be the height of column of liquid A if the density of liquid A is twice the density of liquid B and the height of column of liquid B is 10 cm?

1. All surface areas will experience same force.

2. Surface area with maximum value will experience maximum force

3. None of the above

4. Surface area with minimum value will experience maximum force

Q.

Four containers contain water at the same height as shown in the figure below. Rank them according to the pressure exerted at the bottom of the containers in ascending order.

1. 4, 3, 2, 1

2. 1, 2, 3, 4

3. 2, 3, 4, 1

4. None of these