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.
31. Which of the following units is the smallest in terms of length?
[A] micron
[B] nanometer
[C] fermi
[D] angstrom
Show Answer
Correct Answer: C [ fermi ]
Notes:
Out of the given options, fermi is the smallest unit for measurement of distance. 1 micron = 10-6 m 1 nanometre = 10-9 m 1 angstrom = 10-10m 1 fermi = 10-15m The above four units are used for the measurement of small distances.
32. Which of the following physical quantities do not have any unit of measurement?
[A] Universal Constant of Gravitation
[B] Specific Gravity
[C] Tension
[D] Plancks constant
Show Answer
Correct Answer: B [ Specific Gravity ]
Notes:
Specific Gravity does not have any unit of measurement Specific Gravity = Density of body/ Density of water at 4°C It is the ratio between the density of an object and a reference substance. Based on the value of specific gravity , we can tell whether the object will sink or float in our reference substance.
33. Light year is a unit of which of these following?
[A] distance
[B] time
[C] pressure
[D] power
Show Answer
Correct Answer: A [ distance ]
Notes:
Light year is a unit of distance. One light year is the distance travelled by light in vacuum in one year. 1 light year = 9.46 x 1015 m velocity of light in vacuum = 3 x108 m/s
34. What is the slope of the velocity-time graph when an object moves with constant negative acceleration, having positive initial velocity?
[A] 90°
[B] more than 90°
[C] less than 90°
[D] 0°
Show Answer
Correct Answer: B [more than 90°]
Notes:
When an object moves with constant negative acceleration, having positive initial velocity, the velocity-time graph is a straight line having slope more than 90°. When an object moves with constant positive acceleration, having positive initial velocity, the velocity-time graph is a straight line having slope less than 90°.
35. Which of the following is correct about Kinetic energy during the projectile motion?
[A] it is minimum at the point of projection
[B] it is minimum at the highest point
[C] it is maximum at the highest point
[D] it is minimum at the point of reaching the ground
Show Answer
Correct Answer: B [it is minimum at the highest point]
Notes:
The Kinetic energy of an object is maximum at the point of projection or at the point of reaching the ground. It is minimum at the highest point.
36. Which of the following is/are independent of mass during the projectile motion?
[A] Time of Flight
[B] Horizontal Range
[C] Maximum Height
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
The Time of Flight, Horizontal Range and the Maximum Height of an object are independent of mass of the object during the projectile motion.
37. Which of the following is correct about the coefficient of limiting friction between any two surfaces in contact?
[A] it is equal to twice the tangent of angle of friction
[B] it is equal to twice the sine of angle of friction
[C] it is equal to the tangent of angle of friction
[D] it is equal to the sine of angle of friction
Show Answer
Correct Answer: C [it is equal to the tangent of angle of friction]
Notes:
The coefficient of limiting friction between any two surfaces in contact is equal to the tangent of angle of friction between them. u = tan Q where u = coefficient of limiting friction and Q = angle of friction
38. Angle of friction is _______:
[A] equal to angle of repose
[B] equal to twice the angle of repose
[C] is greater than the angle of repose
[D] is less than the angle of repose
Show Answer
Correct Answer: A [equal to angle of repose]
Notes:
Angle of friction is equal to angle of repose. Angle of repose is the angle that the plane of contact between two bodies makes with the horizontal when the upper body is just on the point of sliding.
39. Which of the following is NOT correct about an inelastic collision?
[A] Linear momentum is conserved
[B] Kinetic energy is conserved
[C] Total energy is conserved
[D] Some or all the forces involved may be non-conservative in nature
Show Answer
Correct Answer: B [Kinetic energy is conserved]
Notes:
Following are the basic characteristics of an inelastic collision: 1. Linear momentum is conserved 2. Kinetic energy is NOT conserved 3. Total energy is conserved 4. Some or all the forces involved may be non-conservative in nature
40. What is the effect on velocities of the two bodies of equal masses when they undergo elastic collision in one dimension?
[A] remains same
[B] gets interchanged
[C] becomes twice of the original velocity
[D] becomes half of the original velocity
Show Answer
Correct Answer: B [gets interchanged]
Notes:
The velocities get interchanged when two bodies of equal masses undergo elastic collision in one dimension.
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