Physics MCQs
Physics Objective (Multiple Choice) General Knowledge & General Science Questions & Answers for SSC-CGL, UPPSC, NDA, CDS and all one day examinations of India.
11. Which of these branches of Physics deal with heat and temperature and their relation to energy and work?
[A] Geophysics
[B] Mechanics
[C] Atomic Physics
[D] Thermodynamics
Show Answer
Correct Answer: D [Thermodynamics]
Notes:
Thermodynamics is that branch of physics which deals with heat and temperature and their relation to energy (such as mechanical, electrical, or chemical energy) and work. The behaviour of these quantities is governed by the four laws of thermodynamics
12. The forces acting at a point are called as:
[A] Collinear forces
[B] Coplanar forces
[C] Concurrent forces
[D] Unit forces
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Correct Answer: C [Concurrent forces]
Notes:
The forces which are acting at a point are called as concurrent forces. Note: When concurrent forces in equilibrium act on a body, the state of the body shall remain unchanged i.e. if the body is at rest, it will continue to be at rest. Similarly, a body will continue to move uniformly along the same straight line, if concurrent forces in equilibrium are applied on the body.
13. What is the rate of acceleration produced by 1 dyne force acting on a body of mass 1 gram?
[A] 9.8 m s-2
[B] 1 m s-2
[C] 1 cm s-2
[D] 9.8 cm s-2
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Correct Answer: C [1 cm s-2]
Notes:
One dyne force is that much force which produces an acceleration of 1 cm s-2 in a body of mass one gram. 1 dyne = 1 g cm s-2 Also, 1 N = 105 dyne
14. The apparent weight of the body becomes zero in which of the following cases in the elevator?
[A] during free fall of a body under gravity
[B] when elevator is accelerating downwards
[C] when elevator is at rest
[D] when elevator is accelerating upwards
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Correct Answer: A [during free fall of a body under gravity]
Notes:
The apparent weight of the body becomes zero in an elevator during free fall of a body under gravity. It can be said that the body becomes weightless as the force of reaction between the person and the plane with which he is in contact vanishes.
15. Which of the following is NOT a conservative force?
[A] Electrostatic force
[B] Magnetic force
[C] Force in an elastic spring
[D] Frictional force
Show Answer
Correct Answer: D [Frictional force]
Notes:
A conservative force is a force with the property that the work done in moving a particle between two points is independent of the taken path. Examples: Electrostatic force, Magnetic force, Force in an elastic spring Frictional force is a non-conservative force.
16. Which of the following has no effect on the pressure beneath the surface of a liquid?
[A] Area of the liquid surface
[B] Density of the liquid
[C] Strength of the gravitational field
[D] Depth of the liquid
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Correct Answer: A [Area of the liquid surface]
Notes:
Pwater = ⍴gh It is clear from the above formula that water pressure only depends on density of water, gravitational acceleration and height of water column.
17. What do we call the maximum velocity of a fluid in a tube for which the flow remains streamlined?
[A] Hyper velocity
[B] critical velocity
[C] stream velocity
[D] laminar velocity
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Correct Answer: B [critical velocity]
Notes:
The maximum velocity of a fluid in a tube for which the flow remains streamlined is called its critical velocity.
18. Which of the following waves are also called as heat waves?
[A] UV rays
[B] X-rays
[C] Infrared
[D] Micro waves
Show Answer
Correct Answer: C [Infrared]
Notes:
Infrared waves vibrate not only the electrons, but entire atoms or molecules of a substance. This vibration increases the internal energy and consequently, the temperature of the substance. Therefore, infrared waves are often called as heat waves.
19. Which of the following represents the total momentum transferred to a surface by an electromagnetic wave?
[A] Total energy transferred/Speed of light
[B] Total energy transferred/ 2 x Speed of light
[C] 2 x Total energy transferred/Speed of light
[D] None of the above
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Correct Answer: A [Total energy transferred/Speed of light]
Notes:
If the total energy transferred to a surface in time t is U, then the magnitude of the total momentum delivered to this surface (for complete absorption) is U/c.
20. In which of the following mediums will sound travel with greater speed at 0° C?
[A] Aluminium
[B] Water
[C] Hydrogen
[D] Same in all of the above
Show Answer
Correct Answer: A [Aluminium]
Notes:
The speed of sound decreases when we go from solid to gaseous state.
