General Science - Physics
Welcome to General Science – Physics MCQ series of GKToday. As of today February 26, 2020, this series has 590 Questions. You may purchase a PDF E-Book compilation comprising all these questions and their answers with explanation from this link.
31. An earth satellite S has an orbit radius which is 2 times that of a communication satellite C. What will be the period of revolution of S?
[A] 1 day
[B] 2 days
[C] 4 days
[D] 8 days
Show Answer
Correct Answer: C [4 days]
Notes:
As per Kepler’s third law, the square of the period of any planet is proportional to the cube of the semimajor axis of its orbit. Ts/Tc = 23/2= 4 days
32. Which of the following strains is produced in a body if the deforming force produces a change in the shape of the body without changing its volume?
[A] Linear
[B] Volumetric
[C] Shearing
[D] All of the above
Show Answer
Correct Answer: C [Shearing]
Notes:
If the deforming force produces a change in the shape of the body without changing its volume, the strain produced in the body is called as shearing strain. Shearing strain is defined as angle in radians through which a plane perpendicular to the fixed surface of the cubical body gets turned under the effect of tangential force.
33. What is the dimensional formula of Stress?
[A] M 1 L-2 T-2
[B] M 1 L-1 T-1
[C] M 1 L1 T-3
[D] M 1 L-1 T-2
Show Answer
Correct Answer: D [M 1 L-1 T-2]
Notes:
Stress is defined as external force per unit area on a body that tends to cause it to deform. The dimensional formula of Stress is M 1 L-1 T-2
34. Which of the following statements represent Hooke’s law?
[A] Stress is directly proportional to strain
[B] Stress is inversely proportional to strain
[C] Stress is equal to strain
[D] None of the above
Show Answer
Correct Answer: A [Stress is directly proportional to strain]
Notes:
According to this law, within the elastic limit, stress is directly proportional to the strain. Therefore, Stress/Strain = constant and is known as modulus of elasticity.
35. 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
Show Answer
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
36. 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
37. Which of the following represents the condition for floatation?
[A] Fb = mg
[B] Fb + mg =0
[C] Fb/ mg =1
[D] Fb = mgh
Show Answer
Correct Answer: A [Fb = mg]
Notes:
As per the Archimedes principle, an object will float if the buoyancy force exerted on it by the fluid balances its weight, i.e. if Fb = mg.
38. What do we call the centre of gravity of the liquid displaced by a body?
[A] fluidic centre
[B] meta-centre
[C] centre of buoyancy
[D] None of the above
Show Answer
Correct Answer: C [centre of buoyancy]
Notes:
The centre of gravity of the fluid which is displaced by an object is known as centre of buoyancy. For stable equilibrium for floating body, the line joining the centre of gravity of the body and centre of floatation should be vertical.
39. Why a small liquid drop is in spherical shape?
[A] due to surface tension
[B] due to low viscosity
[C] due to hydrogen bonding
[D] due to low density
Show Answer
Correct Answer: A [due to surface tension]
Notes:
For a given volume, the sphere has minimum surface area. A small liquid drop has spherical shape as due to surface tension the liquid surface tries to have minimum surface area.
40. Which of the following factors affect the Surface Tension?
[A] Nature of liquid
[B] Area of Surface
[C] Both a and b
[D] None of the above
Show Answer
Correct Answer: A [Nature of liquid]
Notes:
The Surface tension depends only on the nature of liquid and is independent of the area of surface or length of line considered. Surface tension of a liquid is measured by the force acting per unit length on either side of an imaginary line drawn on the free surface of liquid.
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