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.
51. What is the body called which does not have any tendency to recover its original configuration, on the removal of deforming force?
[A] Perfectly plastic
[B] Perfectly elastic
[C] Perfectly ductile
[D] None of the above
Show Answer
Correct Answer: A [Perfectly plastic]
Notes:
Perfectly plastic: If the body does not have any tendency to recover its original configuration, on the removal of deforming force, it is said to be perfectly plastic. Paraffin wax, wet clay can be the closest example of the perfectly plastic body.
52. Which of the following is the unit of Strain?
[A] Newton
[B] Kg
[C] Watt
[D] None of the above
Show Answer
Correct Answer: D [None of the above]
Notes:
As Strain is the ratio of two like quantities, it has no dimensions and units. Strain = Change in configuration/Original configuration
53. 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
54. 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
55. In which form is the work done in stretching a wire stored as?
[A] Kinetic energy
[B] Potential energy
[C] Heat energy
[D] Electrical energy
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Correct Answer: B [Potential energy]
Notes:
In stretching a wire work is done against internal restoring forces. This work is stored in the wire as elastic potential energy. It is also known as strain energy
56. What is the maximum stress after which the wire breaks called as?
[A] Tensile strength
[B] Shear strength
[C] Bulk strength
[D] Hooke’s strength
Show Answer
Correct Answer: A [Tensile strength]
Notes:
The maximum stress after which the wire begin to flow and breaks, is called breaking stress or tensile strength. The force by application of which the wire breaks is called the breaking force.
57. On which of the following factors the breaking stress depends?
[A] Area of cross-section
[B] length of the material
[C] Nature of the material
[D] None of the above
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Correct Answer: C [Nature of the material]
Notes:
Breaking force = P × A Here P is a constant of proportionality and known as breaking stress. Breaking stress is constant for a given material and does not depend upon the dimension (length or thickness) of wire.
58. What is the order of distance for Vander Wall forces to be active?
[A] 10–6 metre
[B] 10–7 metre
[C] 10–8 metre
[D] 10–9 metre
Show Answer
Correct Answer: D [10–9 metre]
Notes:
The forces between the molecules because of the electrostatic interaction between the charges of the molecules are called intermolecular forces. These forces are also called Vander Waal forces. They are quite weak as compared to inter-atomic forces. These forces are also electrical in nature. They are active if the separation between two molecules is of the order of molecular size i.e. 10–9 metre.
59. Who invented mercury barometer?
[A] Blaise Pascal
[B] Daniel Bernoulli
[C] Albert Einstein
[D] Evangelista Torricelli
Show Answer
Correct Answer: D [Evangelista Torricelli]
Notes:
Evangelista Torricelli devised for the first time a method for measuring atmospheric pressure. A long glass tube closed at one end and filled with mercury is inverted into a trough of mercury. This device is known as ‘mercury barometer’.
60. What is the S.I unit of Pressure?
[A] N/Kg m2
[B] N/m
[C] N/m3 s
[D] N/m2
Show Answer
Correct Answer: D [N/m2]
Notes:
The SI unit of pressure is N/m2 It has been named as Pascal (Pa) in honour of the French scientist Blaise Pascal for carrying out pioneering studies on fluid pressure. Its dimensions are M L-1T -2
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