Question

The common name for gas and liquid _______
(A) Solenoid
(B) Cuboid
(C) Void
(D) Fluid.

Answer 1

Solenoid is related to electricity. It is made up of wires.
1. Cuboid is a solid object having specific height, width and length.
2. Void means hollow or empty space.
3. Fluid is something having no fixed shape and can easily flow.

Complete step by step answer:
Let us consider the given options and find which is the common name of gas or liquid:
Solenoid is related to electricity as well as magnetism. It is made up of wires and acts as a magnet when current passses through the wire. So it has no relation with gas or liquid. Hence, this option is wrong.
Cuboid is a solid object having specific height, width and length. So it also has no connection with gas or liquid. Hence this option is also wrong.
Void means hollow or empty space. In physics, void spaces are imagined to solve many problems. Ideally void space is not real. Moreover it is also not related to liquid or gas. Hence this option is also wrong.
A liquid has a definite volume but has no shape of its own. It assumes the shape of the container. The free surface of a liquid is approximately horizontal. Liquids are highly incompressible. The most common liquid considered hydrostatic is water. Its properties are almost closer to an ideal fluid. Gases are highly compressible and have an enormous capacity for expansion. They expand freely and occupy any volume.

From all these observations we can say, the common name for gas and liquid is fluid. Fluids can have the capacity to flow.

Thus the correct option is (D).

Additional information:
A fluid always exerts a force on any surface in contact with it. The force so exerted is always normal to that surface. The normal force exerted by a fluid on any surface in contact with it is called fluid thrust on that surface.

Note:
Properties of ideal fluids:
Incompressible: means it does not get compressed. If we apply pressure on a liquid then its volume should not change and is called incompressible.
Non-viscous: means there is no tangential force among liquid layers that has no frictional force. No resistance for the liquid flow.
In liquids, the intermolecular distances are generally larger than in solids. Hence the intermolecular forces tend to be weaker in liquids than in solids. Many liquids are, like solids, relatively incompressible. So liquids cannot support shearing stresses, because layers of the liquid can easily slide over one another.
Pressure at a point is defined as the normal force or fluid thrust per unit area around that point. If the thrust is uniform, the pressure at every point of the surface is the same. But if the thrust is variable the pressure at different points of the surface will vary.