Physics MCQs
Physics Objective (Multiple Choice) General Knowledge & General Science Questions & Answers for SSC-CGL, UPPSC, NDA, CDS and all one day examinations of India.
11. 1 kilogram force produces how much acceleration in a body of mass 1 kg?
[A] 1 ms-2
[B] 0
[C] 9.8 ms-2
[D] -1 ms-2
Show Answer
Correct Answer: C [9.8 ms-2]
Notes:
1 Kilogram force or 1 Kilogram weight is that much force which produces an acceleration of 9.8 ms-2 in a body of mass 1 kg. Also, 1 kg wt. or 1 kg f = 9.8 N
12. The energy by virtue of its position is known as:
[A] Kinetic energy
[B] Potential energy
[C] Internal energy
[D] Heat energy
Show Answer
Correct Answer: B [Potential energy]
Notes:
The energy by virtue of its position is known as Potential energy. The energy by virtue of its motion is known as Kinetic energy.
13. What happens to the velocity of a light body when it undergoes an elastic collision in one dimension with a very heavy body at rest?
[A] its velocity becomes twice
[B] it rebounds with twice of its own velocity
[C] it rebounds with its own velocity
[D] it stops and comes to rest
Show Answer
Correct Answer: C [it rebounds with its own velocity]
Notes:
A light body rebounds with its own velocity when it undergoes an elastic collision in one dimension with a very heavy body at rest. Note: The heavy body continues to be in rest in this case
14. What is the gravitational potential energy for infinite distance?
[A] 0
[B] infinity
[C] 9.8 J
[D] None of the above
Show Answer
Correct Answer: A [0]
Notes:
The gravitational potential energy of a body at a point is defined as the amount of work done in bringing the body from infinity to that point against the gravitational force. U = – GMm/r When r =infinity, then U =0
15. What do we call the minimum velocity with which a body must be projected up, so as to enable it to just overcome the gravitational pull?
[A] Orbital velocity
[B] Gravitational velocity
[C] Escape velocity
[D] None of the above
Show Answer
Correct Answer: C [Escape velocity]
Notes:
The minimum velocity with which a body must be projected up, so as to enable it to just overcome the gravitational pull, is known as Escape velocity. Ve = (2gR)1/2
16. Which of the following is the orbital velocity of a satellite orbiting very close to the surface of earth?
[A] 7.92 km/s
[B] 9.8 km/s
[C] 11.2 km/s
[D] 14.8 km/s
Show Answer
Correct Answer: A [7.92 km/s]
Notes:
In this case, the radius of the orbit will be nearly equal to the radius of earth. The orbital velocity of a satellite orbiting very close to the surface of earth is 7.92 km/s.
17. 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.
18. The Kinetic energy of a satellite is maximum in which of the following conditions?
[A] when the satellite is at perigee
[B] when the satellite is at apogee
[C] it is equal at perigee and apogee
[D] None of the above
Show Answer
Correct Answer: A [when the satellite is at perigee]
Notes:
The Kinetic energy will be maximum when the satellite is closest to the central body (at perigee) and minimum when it is farthest from the central body (at apogee). Potential energy will be minimum when kinetic energy = maximum i.e., the satellite is closest to the central body (at perigee) and maximum when kinetic energy = minimum i.e., the satellite is farthest from the central body (at apogee).
19. 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
20. What happens to the viscosity of a liquid with increase in temperature?
[A] it increases
[B] it decreases
[C] it may increase or decrease
[D] No change
Show Answer
Correct Answer: B [it decreases]
Notes:
The viscosity of liquids decreases with increase in temperature, while it increases in the case of gases.
