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.
41. What is the SI unit of acceleration due to gravity?
[A] ms-2
[B] ms-3
[C] Kgms-2
[D] ms-1
Show Answer
Correct Answer: A [ms-2]
Notes:
The acceleration due to gravity is the acceleration set up in the body when it falls freely under the effect of gravity alone. The SI unit of acceleration due to gravity is ms-2
42. Which of the following is true about the effect of altitude on the value of acceleration due to gravity?
[A] The acceleration due to gravity decreases with height
[B] The acceleration due to gravity increases with height
[C] The acceleration due to gravity is not dependent on height
[D] None of the above
Show Answer
Correct Answer: A [The acceleration due to gravity decreases with height]
Notes:
The acceleration due to gravity decreases with height. G0= g(1-2h/R) where h is the height above the surface of the earth.
43. The value of acceleration due to gravity is minimum on which of these planets?
[A] Mars
[B] Jupiter
[C] Mercury
[D] Neptune
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Correct Answer: C [Mercury]
Notes:
The value of acceleration due to gravity is minimum on planet Mercury and maximum on planet Jupiter.
44. What is the value of Universal Gravitational Constant?
[A] 6.67×10-9 N–m2 kg–2
[B] 6.67×10-10 N–m2 kg–2
[C] 6.67×1011 N–m2 kg–2
[D] 6.67×10-11 N–m2 kg–2
Show Answer
Correct Answer: D [6.67×10-11 N–m2 kg–2]
Notes:
The value of Universal Gravitational Constant is same throughout the universe and is equal to 6.67×10-11 Nm2 kg-2 in S.I. and 6.67×10-8 dyne cm2 g-2
45. The time period of a satellite does not depend on which of the following?
[A] Radius of earth
[B] Height of the satellite
[C] Mass of the satellite
[D] None of the above
Show Answer
Correct Answer: C [Mass of the satellite]
Notes:
Time period of a satellite is the time taken by satellite to go once around the earth. The time period is independent of the mass of orbiting body and depends on the mass of central body and radius of the orbit.
46. What is the time period for a satellite orbiting close to the surface of earth?
[A] 84.6 minutes
[B] 72.4 minutes
[C] 44.8 minutes
[D] 24 hours
Show Answer
Correct Answer: A [84.6 minutes]
Notes:
In this case, the radius of the orbit will be nearly equal to the radius of earth i.e. 6.4 x 106m. The time period for a satellite orbiting close to the surface of earth is 84.6 minutes.
47. By how much the orbital velocity of Moon has to increase for it to cease to remain the earth’s satellite?
[A] 2 times
[B] 3 times
[C] √2 times
[D] √3 times
Show Answer
Correct Answer: C [√2 times]
Notes:
If the speed of a satellite orbiting close to the earth is made √2 times (or increased by 41%) then it will escape from the gravitational field. Moon is a natural satellite of earth.
48. The distance of Neptune and Saturn from sun are nearly 1013 and 1012 meters respectively. Assuming that they move in circular orbits, what will be the ratio of their periodic times?
[A] 40
[B] 10√10
[C] 20√20
[D] 30√30
Show Answer
Correct Answer: B [10√10]
Notes:
By using Kepler’s third law, Tneptune/Tsaturn = (Rneptune/Rsaturn)3/2
49. What is the name given to the linear strain produced in the direction of deforming force?
[A] Linear strain
[B] Longitudinal strain
[C] Directional strain
[D] Zero strain
Show Answer
Correct Answer: B [Longitudinal strain]
Notes:
Linear strain: If the deforming force produces a change in length alone, the strain produced in the body is called linear strain or tensile strain. Linear strain in the direction of deforming force is called longitudinal strain and in a direction perpendicular to force is called lateral strain.
50. What is Young’s Modulus?
[A] ratio of longitudinal strain to normal stress
[B] product of normal stress of longitudinal strain
[C] ratio of normal stress to longitudinal strain
[D] ratio of normal stress to lateral strain
Show Answer
Correct Answer: C [ratio of normal stress to longitudinal strain]
Notes:
Young’s Modulus is defined as the ratio of normal stress to longitudinal strain within limit of proportionality. Y = normal stress/longitudinal strain
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