State Of Matter

21. "The buoyant force acting on an object partially or wholly immersed in a liquid medium (gas or liquid) is equal to the weight of the liquid displaced by that object." Which is that principle? [S.S.C. Online MTS (T-I) 21.08.2019 (Shift-II)]

(a) Newton's second law of motion
(b) Boyle's principle
(c) Archimedes's principle
(d) Theory of Charles

Correct Answer: (c) Archimedes's principle

Solution:Archimedes' Principle states that an object immersed in a fluid experiences an upward buoyant force equal to the weight of the fluid displaced by the object.

This means that the weight of the object will appear less in a fluid compared to its weight in air.

22. Which law/principle states that when an object is immersed wholly or partially in a liquid, it experiences an upward force, which is equal to the weight of the liquid displaced by the object? [S.S.C. Online C.P.O.S.I. (T-I) 7.07.2017 (Shift-I)]

(a) Boyle's law
(b) Charles' law
(c) Archimedes's principle
(d) Pascal's law

Correct Answer: (c) Archimedes's principle

Solution:The principle that states this is called Archimedes' Principle.

Archimedes' Principle:

"When an object is immersed wholly or partially in a fluid, it experiences an upward buoyant force equal to the weight of the fluid displaced by the object."

This principle explains why objects float or sink and is fundamental in fluid mechanics.

23. Any body kept in fluid experiences an upward force called _______ . [S.S.C. Online CHSL (T-I) 22.03.2018 (Shift-I)]

(a) torque
(b) moment
(c) pressure
(d) upthrust

Correct Answer: (d) upthrust

Solution:

The buoyant force is the upward force exerted by a fluid (liquid or gas) that opposes the weight of an object submerged in it.
Because pressure in a fluid increases with depth, the bottom of the object experiences more pressure than the top, creating a net upward force .

24. According to ________ pressure is equal to the force divided by the area on which it acts. [S.S.C. Online Graduation Level (T-I) 11.06.2019 (Shift-II)]

(a) Stefan-Boltzmann Law
(b) Newton's Law
(c) Hooke's Law
(d) Pascal's Law

Correct Answer: (d) Pascal's Law

Solution:According to Pascal's Law, pressure is equal to the force divided by the area on which it acts.

Pressure (P) = Force (F) / Area (A)

Pascal's Law (or Pascal’s Principle) also states:

“A change in pressure applied to an enclosed fluid is transmitted undiminished to every portion of the fluid and the walls of the containing vessel.”

25. Which law of physics is based on the hydraulic jacks used for lifting loads in industrial installations? [S.S.C. Online Constable GD 1.03.2019 (Shift-III)]

(a) Game theory
(b) Archimedes principle
(c) Newton's law
(d) Pascal's law

Correct Answer: (d) Pascal's law

Solution:The hydraulic jack used for lifting loads in industrial installations is based on Pascal's law of physics.

According to Pascal's law,

if pressure is applied to a fluid, it travels equally in all directions throughout the fluid without decay. The hydraulic jack works on the same principle.

26. Sea water is saltier than rain water because- [S.S.C. Online Graduation Level (T-I) 1.09.2016 (Shift-I)]

(a) Sea animals are salt-producing.
(b) The air around the sea is saltish.
(c) Rivers wash away salts from the earth and pour them into the sea.
(d) Sea beds have salt-producing mines.

Correct Answer: (c) Rivers wash away salts from the earth and pour them into the sea.

Solution:Sea water is saltier than rainwater because it contains accumulated dissolved salts from land and seafloor sources, while rainwater is distilled through evaporation and is nearly salt-free.

27. Which of the following is a characteristic of conservative force? [S.S.C. Online CGL (T-I) 20.08.2021 (Shift-III)]

(a) Energy is dissipated as heat energy.
(b) Work done by it is ultimately recoverable.
(c) Work done by it in a round trip is not zero.
(d) Work done by it depends upon the path.

Correct Answer: (b) Work done by it is ultimately recoverable.

Solution:Conservative force is a force with the property that the total work done in moving a particle between two points is independent of the path followed but depends only on the initial and final positions.

Gravitational force and electrostatic force are also conservative.
The work done by the conservative force on a closed path is zero.