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.
21. The work done in moving a body over a smooth inclined plane does not depend on which of the following?
[A] mass of the body
[B] height of the inclined plane
[C] slope of the inclined plane
[D] All of the above
Show Answer
Correct Answer: C [slope of the inclined plane]
Notes:
The work done in moving a body over a smooth inclined plane does not depend on the slope of the inclined plane. W = mgh in case of smooth inclined plane, where m = mass of the body, g = acceleration due to gravity and h = height of the inclined plane.
22. Which of the following is/are correct about Kinetic energy?
[A] Kinetic energy can be positive or negative
[B] Kinetic energy is independent of frame of reference
[C] Both a and b
[D] None of the above
Show Answer
Correct Answer: D [None of the above]
Notes:
Kinetic energy of a body is half the product of mass of the body and square of the velocity of the body. K.E = 1/2(mv2) Kinetic energy depends on the frame of reference. Kinetic energy of a body is always positive.
23. Which of the following is NOT an example of conservation of mechanical energy?
[A] Vibrations of a simple pendulum
[B] Motion of a small spherical ball over a watch glass
[C] Vibrations of an elastic spring
[D] None of the above
Show Answer
Correct Answer: D [None of the above]
Notes:Some examples of conservation of mechanical energy:
- Vibrations of a simple pendulum
- Motion of a small spherical ball over a watch glass
- Vibrations of an elastic spring
24. Which of the following is incorrect:
[A] Gravitational force of attraction is independent of nature of intervening medium
[B] Gravitational forces are central forces
[C] Gravitational forces are non-conservative forces
[D] All of the above
Show Answer
Correct Answer: C [Gravitational forces are non-conservative forces]
Notes:Characteristics of Gravitational Forces:
- It is always attractive in nature.
- It is independent of the medium between the bodies.
- It holds good over a wide range of distances
- It is a central force i.e. acts along the line joining the centres of two interacting bodies
- The gravitational force between two particles is independent of the presence or absence of other bodies
- It is the weakest force in nature.
- It is a conservative force i.e. work done by it is path independent or work done in moving a particle round a closed path under the action of gravitational force is zero.
- It is an action-reaction pair.
25. Which of the following is correct about acceleration due to gravity?
[A] it increases with depth
[B] it decreases with depth
[C] it is independent of depth
[D] None of the above
Show Answer
Correct Answer: B [it decreases with depth]
Notes:
The value of acceleration due to gravity decreases with depth. g0= g(1-d/R) where d is the depth below the centre of the earth.
26. What will be the effect on the value of acceleration due to gravity at the poles if the rate of rotation of earth increases?
[A] No effect
[B] it will increase
[C] it will decrease
[D] it will become zero
Show Answer
Correct Answer: A [No effect]
Notes:
If the rate of rotation of earth increases then the value of acceleration due to gravity decreases at all the places on the surface of earth except at poles.
27. Choose the correct statement about weight:
[A] It is a scalar quantity
[B] Its value is independent of g
[C] It is determined by a spring balance
[D] None of the above
Show Answer
Correct Answer: C [It is determined by a spring balance]
Notes:
Weight is the attractive force exerted by earth on any body. Its value changes with g. It is determined by a spring balance. It is a vector quantity.
28. On which of the following the escape velocity of a body does not depend?
[A] Mass of the body
[B] Radius of the planet
[C] Mass of the planet
[D] None of the above
Show Answer
Correct Answer: A [Mass of the body]
Notes:
The escape velocity is independent of the mass and angle of projection of the body. Escape velocity depends on the mass and radius of the planet from the surface of which the body is to be projected.
29. The angular momentum of a satellite depends on which of the following?
[A] Mass of the satellite
[B] Mass of the planet
[C] Radius of orbit of satellite
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:
The angular momentum of a satellite depends on: 1. Mass of the satellite 2. Mass of the planet 3. Radius of orbit of satellite it is denoted by L. L = (m2GMr)1/2
30. Which of the following is an essential condition for geostationary satellites of earth?
[A] It should rotate from west to east
[B] Its period of revolution should be 24 hours
[C] It should be at a height of nearly 36000 km above the equator
[D] All of the above
Show Answer
Correct Answer: D [All of the above]
Notes:Essential condition for geostationary satellites of earth:
- Its sense of rotation should be the same as that of earth i.e. it should rotate from west to east.
- It should be at a height of nearly 36000 km above the equator.
- Its period of revolution should be 24 hours.
- it should revolve in an orbit concentric and coplanar with the equatorial plane.
- Its orbital velocity is nearly 3.1 km/s
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