(English Medium) ICSE Class 9 - CISCE Question Bank Solutions for Physics

Complete the following sentence :

Pressure of a liquid at a given depth is .................. To the density of the liquid.

The S.I. unit of pressure is : 

The pressure inside a liquid of density p at a depth h is : 

The pressure P₁ at a certain depth in river water and P₂ at the same depth in sea water are related as :

The pressure P₁ at the top of a dam and P₂ at a depth h form the top inside water (density p) are related as : 

A hammer exerts a force of 1.5 N on each of the two nails A and B. The area of cross section of tip of nail A is 2 mm² while that of nail B is 6 mm². Calculate pressure on each nail in pascal.

A block of iron of mass 7.5 kg and of dimensions 12 cm × 8 cm × 10 cm is kept on a table top on its base of side 12 cm × 8 cm.

Calculate:

1. Thrust and
2. Pressure exerted on the table top

Take 1 kgf = 10 N.

A vessel contains water up to a height of 1.5 m. Taking the density of water 10³ kg m^-3, acceleration due to gravity 9.8 m s^-2 and area of base of vessel 100 cm², calculate: (a) the pressure and (b) the thrust at the base of vessel.

The area of base of a cylindrical vessel is 300 cm². Water (density= 1000 kg m^-3) is poured into it up to a depth of 6 cm. Calculate : (a) the pressure and (b) the thrust of water on the base. (g = 10m s^-2.

1. Calculate the height of a water column which will exert on its base the same pressure as the 70 cm column of mercury. Density of mercury is 13.6 g cm^-3.
2. Will the height of the water column in part (a) change if the cross-section of the water column is made wider?

The pressure of water on the ground floor is 40,000 Pa and on the first floor is 10,000 Pa. Find the height of the first floor. (Take : density of water = 1000 kg m^-3, g = 10 m s^-2)

A simple U tube contains mercury to the same level in both of its arms. If water is poured to a height of 13.6 cm in one arm, how much will be the rise in mercury level in the other arm?

Given : density of mercury = 13.6 x 10³ kg m^-3 and density of water = 10³ kg m^-3.

(i) The diameter of neck and bottom of a bottle are 2 cm and 10 cm, respectively. The bottle is completely filled with oil. If the cork in the neck is pressed in with a force of 1.2 kgf, what force is exerted on the bottom of the bottle?

(ii) Name the law/principle you have used to find the force in part (a).

Two cylindrical vessels fitted with pistons A and B of area of cross-section 8 cm² and 320 cm² respectively are joined at their bottom by a tube and they are completely filled with water. When a mass of 4 kg is placed on piston A, Find:

1. the pressure on piston A,
2. the pressure on piston B, and
3. the thrust on piston B.

What do you understand by the term upthrust of a fluid? Describe an experiment to show its existence. 

In what direction and at what point does the buoyant force on a body due to a liquid act? 

What is meant by the term buoyancy? 

Define upthrust and state its S.I. unit. 

What is the cause of upthrust? At which point can it be considered to act? 

Why is a force needed to keep a block of wood inside water?