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.
1. Which of the following term denotes the internal reaction force per unit area developed as a result of applied external force ?
[A] Stress
[B] Friction
[C] Moment of Inertia
[D] tension
Show Answer
Correct Answer: A [Stress]
Notes:
Stress is the force acting per unit area. It is the internal force reaction per unit area developed as a result of external force.
2. On which of the following Inertia of an object depends ?
[A] Bulk
[B] Size
[C] Shape
[D] Mass
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Correct Answer: D [Mass]
Notes:
Inertia is the resistance experienced by an object to any change in its velocity. This includes changes to the object’s speed, or direction of motion. Inertia of rest, Inertia of motion are the examples.
3. “Svedberg Unit” is a measure of?
[A] Concentration
[B] Size
[C] Density
[D] Time
Show Answer
Correct Answer: D [Time]
Notes:
A Svedberg unit (S/ Sv) is utilized to denote sedimentation coefficients, providing specific measurement of a particle based on its sedimentation rate under acceleration. Essentially, it computes how quickly a particle settles to the bottom of a solution. In terms of the time dimension, a Svedberg unit amounts to exactly 10−13 seconds, indicating that it is essentially a measure of time.
4. If earth stops rotating, the impact on weight of a body will be minimum on which among the following places?
[A] Equator
[B] North Pole
[C] Tropic of Cancer
[D] Tropic of Capricorn
Show Answer
Correct Answer: B [North Pole]
Notes:
The question is related to the centrifugal forces, which represent the effects of inertia that arise in connection with rotation and which are experienced as an outward force away from the center of rotation. The impact of this force is maximum at Equator and minimum at Pole.
5. What is the work done by centripetal force in case of Uniform Circular Motion?
[A] 1 joule
[B] 0 joule
[C] Depends on the magnitude of Force
[D] None of the above
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Correct Answer: B [0 joule]
Notes:
The work done by Centripetal Force in case of Uniform Circular Motion is zero. The displacement and force are mutually perpendicular to each other in case of centripetal force. Therefore the work done is zero.
6. Which of the following statements regarding vectors is NOT correct?
[A] A unit vector is dimensionless
[B] A vector cannot be divided by a vector
[C] A vector changes, when it is displaced to itself
[D] Current is not a vector quantity
Show Answer
Correct Answer: C [A vector changes, when it is displaced to itself]
Notes:
A unit vector is unit less and dimensionless. A vector cannot be divided by a vector as a vector cannot be divided by a direction. A vector does not change, when it is displaced to itself. Time, Pressure, Surface Tension, Current are some of the quantities that have direction but are not vectors. A physical quantity is a vector only when it follows commutative law of addition of vectors.
7. The Newton’s third law is applicable when:
[A] bodies are at rest
[B] bodies are in motion
[C] bodies are in the air
[D] bodies are at rest or in motion
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Correct Answer: D [bodies are at rest or in motion]
Notes:
The Newton’s third law is applicable whether the bodies are at rest or in motion. It states that to every action there is an equal and opposite reaction.
8. Which of the following is true about universal gravitational constant in the case of two bodies each of unit mass having their centres placed at unit distance apart?
[A] It is equal to the force of attraction between them
[B] It is equal to twice the force of attraction between them
[C] It is equal to half the force of attraction between them
[D] It is equal to ten times the force of attraction between them
Show Answer
Correct Answer: A [It is equal to the force of attraction between them]
Notes:
The universal gravitational constant is equal to the force of attraction between two bodies each of unit mass having their centres placed at unit distance apart. F = Gm1m2/r When m1 and m2 = 1 and r=1 then F=G.
9. Which of the following factors do not affect the value of modulus of elasticity of a body?
[A] Nature of material
[B] Temperature of the body
[C] Length and volume and of the body
[D] None of the above
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Correct Answer: C [Length and volume and of the body]
Notes:
Modulus of elasticity (E) depends upon the nature of material of the body and the manner in which the body is deformed. Modulus of elasticity (E) depends upon the temperature of the body. Modulus of elasticity (E) is independent of the dimensions (length, volume etc.) of the body
10. Which of the following is the S.I. unit of density?
[A] m-2
[B] m-3
[C] kg m-2
[D] kg m-3
Show Answer
Correct Answer: D [ kg m-3 ]
Notes:
The SI unit of density is kg m-3. It is a positive scalar quantity. The Gaussian unit of density is the gram per cubic centimeter which is equivalent to a gram per milliliter [1 g/cm3 = 1 g/ml].
