Upthrust in Fluids, Archimedes' Principle and Floatation

The property of a liquid to exert an upward force on a body immersed in it is called :

• buoyancy

• pressure

• friction

• viscosity

Answer explanation

The upward force a liquid exerts on an immersed body is known as buoyancy. This property allows objects to float or sink depending on their density relative to the liquid.

If an empty can is pushed into water, we feel :

• a downward force

• an upward force

• it is easy to push the can into water

• nothing

The effect of upthrust is that the weight of a body immersed in a liquid appears to be :

• more than its actual weight

• the same as its weight outside the liquid

• less than its actual weight

• None of these

Which of the following are the correct characteristic properties of upthrust ?

(i) the smaller the volume of a body submerged in a liquid, the smaller is the upthrust

(ii) the upthrust acts on the body in an upward direction at the centre of buoyancy

(iii) for the same volume of a body inside a fluid, the less the density of the fluid, greater will be the upthrust

• (i) & (ii)

• (i) & (iii)

• (ii) & (iii)

• (i), (ii) & (iii)

The S.I. unit of upthrust is:

• Pa

• N

• kg

• kg m2

Archimedes' principle applies on :

• solids and liquids

• liquids and gases

• solids and gases

• solids, liquids and gases

If a body is completely immersed in a liquid, the volume of the liquid displaced will be ............... its own volume and the upthrust will be ...............

• less than, minimum

• equal to, minimum

• more than, maximum

• equal to, maximum

The apparent loss in weight is equal to the upthrust on the body verifies :

• Pascal's law

• Newton's third law

• Archimedes' principle

• Newton's second law

A body weighed 'W' in air by a sensitive spring balance, will weigh ............... in vacuum.

• the same

• slightly more

• slightly less

• zero

Floating of a cork on the surface of water indicates that :

• the density of water is more than the density of cork.

• the density of water is less than the density of cork.

• the density of water is equal to the density of cork.

• the density of water plays no role in the floatation of cork.