Question

What do you mean by thrust or buoyant force?
(A) The upward force exerted by liquid when a body is immersed in the liquid.
(B) The downward force exerted by the liquid when a body is immersed in the liquid.
(C) The upward force exerted by the body when a body is immersed in the liquid.
(D) The downward force exerted by the body when a body is immersed in the liquid.

Answer 1

Hint
Force is the push or pull of an object over a distance. The word buoyant means floatable if an object has to float it is understandable that a force is needed from downwards to make it float. This is known as buoyant force.

Complete step by step answer
When an object is immersed in any fluid the object experiences a force from downwards that pushes the object upwards, normally the gravitational force pushes the object downwards i.e. towards the earth. But the objects immersed in fluid experience an opposite force that pushes the object towards the surface which is known as buoyant force. The phenomenon of experiencing an upward force by the object is called buoyancy.
Technically buoyant force is defined as the upward force exerted by the fluid when an object is immersed in the liquid. The unit of buoyant force is Newton. The point where the upward force is exerted is known as the centre of buoyancy.
Example of buoyancy
- Ship floating in the water
- If we put an egg inside the water we can see the egg floats in the water.
Not all the objects experience the buoyant force if the buoyancy is less than the object’s weight the object sinks. If the buoyancy is equal to than the object's weight the object is suspended in the fluid. The object floats if the buoyancy is higher than the object’s weight.
Hence, the correct answer is option A) the upward force exerted by liquid when a body is immersed in the liquid.

Note
The buoyant force depends on the density of the fluid in which the object is submerged, acceleration due to gravity and volume of the displaced fluid. The buoyant force is always present in the object which is immersed in fluid whether the object floats, sinks or is suspended.