General Science – Physics MCQs
Physics Objective (Multiple Choice) General Knowledge & General Science Questions & Answers for SSC-CGL, UPPSC, UPSC, NDA, CDS and UPSC Civil Services Prelims Examinations.
11. Which of the following statements is correct about the value of acceleration due to gravity (g) in a light and heavy falling body?
[A] the value of g will be greater in the light body
[B] the value of g will be greater in the heavy body
[C] the value of g will be equal in both the bodies
[D] the value of g depends on the mass
Show Answer
Correct Answer: C [the value of g will be equal in both the bodies]
Notes:
Acceleration due to gravity is independent of mass, shape, size etc. of falling body. Therefore, a light and heavy body will have equal acceleration.
12. Which of the following has an effect on the value of acceleration due to gravity?
[A] Shape of the earth
[B] Height above the earth surface
[C] Axial rotation of the earth
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
The value of acceleration due to gravity vary due to the following factors : (a) Shape of the earth (b) Height above the earth surface (c) Depth below the earth surface (d) Axial rotation of the earth
13. Which of the following is incorrect about a satellite?
[A] It is a freely falling body
[B] it does not require energy for its motion in orbit
[C] it suffers an acceleration
[D] it moves with constant speed
Show Answer
Correct Answer: C [it suffers an acceleration]
Notes:
A satellite is a freely falling body. it does not require energy for its motion in orbit and its speed is constant.
14. Which of these statements is correct about the energy of a satellite:
[A] Potential energy= – 2 (Kinetic energy)
[B] Potential energy= 2 (Kinetic energy)
[C] Potential energy= – 3 (Kinetic energy)
[D] Potential energy= – (Kinetic energy)
Show Answer
Correct Answer: A [Potential energy= – 2 (Kinetic energy)]
Notes:
Potential energy of a satellite: -L2/mr2 Potential energy of a satellite: -L2/2mr2 Therefore, Potential energy= – 2 (Kinetic energy)
15. If the time of revolution is T in a satellite, then kinetic energy is proportional to which of the following:
[A] T-4/3
[B] T2/3
[C] T-2/3
[D] T-1/3
Show Answer
Correct Answer: C [T-2/3]
Notes:
The square of the period of any planet is proportional to the cube of the semimajor axis of its orbit. So r is inversely proportional to cube root of the square of T. And Kinetic energy is inversely proportional to r. Therefore, K.E is directly proportional to (T)-2/3
16. What is the internal restoring force acting per unit area of cross section of the deformed body called?
[A] Strain
[B] Stress
[C] Pressure
[D] Surface Tension
Show Answer
Correct Answer: B [Stress]
Notes:
Stress is the internal restoring force acting per unit area of cross section of the deformed body. Stress is given by Force/Area.
17. What is the unit of Stress?
[A] N/m
[B] Kg/m
[C] Nm
[D] It has no units
Show Answer
Correct Answer: A [N/m]
Notes:
If an external force F is applied on the area A of a body then, Stress is given by Force/Area Units of Stress: S.I unit: N / m C.g.s unit: dyne / cm
18. Which of the following statements is correct?
[A] Bulk stress occurs only in liquids
[B] Longitudinal stress occurs only in solids
[C] Both a and b
[D] None of the above
Show Answer
Correct Answer: B [Longitudinal stress occurs only in solids]
Notes:
Longitudinal stress occurs only in solids. It comes in picture only when one of the three dimensions viz. length, breadth, height is much greater than other two.
19. What is the force that is required to produce unit elongation in a wire known as?
[A] Bulk modulus
[B] Thermal strain
[C] Thermal stress
[D] Force constant
Show Answer
Correct Answer: D [Force constant]
Notes:
Force constant of material of wire is the force required to produce unit elongation in a wire. It is denoted by k. K = F/l or K = YA/l
20. What is the ratio of normal stress to the volumetric strain within the elastic limits is called as?
[A] Bulk Modulus
[B] Young Modulus
[C] Modulus of Rigidity
[D] None of the above
Show Answer
Correct Answer: A [Bulk Modulus]
Notes:
The ratio of normal stress to the volumetric strain within the elastic limits is called as Bulk modulus. It is denoted by K.
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