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.
11. The International Astronomical Union (IAU) considers an object to be a dwarf planet if:
- It orbits a star
- It has enough mass for its gravity to overcome external forces to acquire a near-spherical shape
- It doesn’t have bigger objects in its neighbourhood
Select the correct option from the codes given below:
[A] Only 1 & 2
[B] Only 2 & 3
[C] Only 1 & 3
[D] 1, 2 & 3
Show Answer
Correct Answer: A [ Only 1 & 2]
Notes:
(1) A planet is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit. (2) A “dwarf planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, (c) has not cleared the neighborhood around its orbit, and (d) is not a satellite. (3) All other objects, except satellites, orbiting the Sun shall be referred to collectively as “Small Solar System Bodies.”
12. Which among the following is / are correct statements:
1. A sail boat can be propelled by air blown at the sail from a big fan attached to the boat
2. All type of waves exhibit diffraction
3. Potatoes, maize, barley, rice can be used for commercial production of Ethanol
Select the correct option from the codes given below:
[A] Only 1 & 2
[B] Only 2 & 3
[C] Only 1 & 3
[D] 1, 2 & 3
Show Answer
Correct Answer: B [ Only 2 & 3]
Notes:
The first statement is not correct because the action of the air from the fan and reaction of the sail both would act on the boat itself.
13. A person runs up two flights of stairs instead of walking up. The person feels more tired because ___?
[A] He does more work when he runs in comparison to when he walks
[B] His power output is greater when he runs in comparison to when he walks
[C] His gravitational force is greater when he runs in comparison to when he walks
[D] He has more inertia when he runs in comparison to when he walks
Show Answer
Correct Answer: B [ His power output is greater when he runs in comparison to when he walks]
Notes:
Energy required during running up two flights of stairs is much higher than the time of walking up. It needs more energy and that is why the person feels more tired.
14. Consider the following statements with respect to LIGO project, which is sometimes seen in news:
- LIGO project helps to understand Earth’s interior by studying seismic waves.
- India is a partner in LIGO project.
Which of the above statements is/are correct?
[A] Only 1
[B] Only 2
[C] Both 1 & 2
[D] Neither 1 nor 2
Show Answer
Correct Answer: B [ Only 2]
Notes:
First statement is incorrect because LIGO project is related to study of gravitational waves in space. Second statement is correct. Also, we note that LIGO-India, or INDIGO, is a planned collaborative project between the LIGO Laboratory and the Indian Initiative in Gravitational-wave Observations (IndIGO) to create a world-class gravitational-wave detector in India.
15. If the time taken in an echo is 5 seconds, which among the following will be the approximate distance of the object from source of sound? (assume normal room temperature at 20°C)
[A] 1715 meters
[B] 1256 meters
[C] 857 meters
[D] 554 meters
Show Answer
Correct Answer: C [ 857 meters]
Notes:
The time taken by the sound waves in going and coming back is 5 seconds, i.e. 2.5 second to reach and 2.5 seconds to come back. So the object is placed 343 x 2.5= 857 meters
16. Which among the following play role in the formation of Rainbow?
1. Dispersion
2. Total Internal Reflection
3. Refraction
Select the correct option from the codes given below:
[A] Only 1 & 2
[B] Only 2 & 3
[C] Only 1 & 3
[D] 1, 2 & 3
Show Answer
Correct Answer: D [ 1, 2 & 3]
Notes:
1, 2 & 3 are correct
17. The speed of an artificial satellite depends upon:
- Mass of the satellite
- Radius of orbit for the satellite
- Mass of the central body about which the satellite orbits
- Gravitational constant
Select the correct option from codes given below:
[A] Only 2 & 3
[B] Only 2, 3 & 4
[C] Only 1, 2 & 4
[D] 1, 2, 3 & 4
Show Answer
Correct Answer: B [ Only 2, 3 & 4]
Notes:
V=√ GM/r
G is the Gravitational constant
M is the mass of the central body about which the satellite orbits
R is the Radius of orbit for the satellite
V is the velocity of satellite
18. Consider the following physical quantities:
- Entropy
- Work
- Momentum
- Force
Which of the above are vector quantities?
[A] 1 & 2
[B] 2 & 3
[C] 3 & 4
[D] 1 & 4
Show Answer
Correct Answer: C [ 3 & 4]
Notes:
A quantity which depends on direction is called a vector quantity. A quantity which does not depend on direction is called a scalar quantity. Entropy and work are scalar quantities.
19. In terms of Physics, which among the following situations result in work done?
- Brakes are applied to a moving vehicle and vehicle stops
- A ball is projected vertically upward and it comes back due to force of gravity
- A body moves in a circular path
Select the correct option from the codes given below:
[A] Only 1 & 2
[B] Only 2 & 3
[C] Only 1 & 3
[D] 1, 2 & 3
Show Answer
Correct Answer: A [ Only 1 & 2]
Notes:When a body is acted upon by a force, there are two conditions when work done is zero. Firstly, the force must not cause displacement in its own direction; secondly, the force must act at right angle to direction of displacement. However, the work can be positive or negative. Positive work is done, when the angle between the direction of force applied and the displacement of body is zero. For example, when a horse pulls a cart or an engine pulls a train, the positive work is done. Negative work is done, when the angle between the direction of the force applied and the displacement is 180° i.e., the displacement is in a direction opposite to the force. For example, when brakes are applied to a moving vehicle, the work done by the applied force is negative. Similarly, when a ball is projected vertically upward, the work done by the force of gravity is negative. When a body moves in a circular path, no work is done. It is because, the centripetal force acting on the body is always at right angles to the displacement of the body along the circular path.
Thus, cos 90° = 0
So, in the expression
W = F cos 90° × S = 0 × S = Zero
At the same time, we note that when satellite revolves around the earth in a circular orbit. Work done by the force due to gravity is zero, because it acts at right angles to the direction of displacement of the satellite
20. In which of the following respects, the ultra-violet radiations are similar to white light?
- Both obey the laws of reflection and refraction
- Both travel with same speed in vacuum
- Both are equally active chemically
- Both are scattered equally
Select the correct option from the codes given below:
[A] Only 1
[B] Only 1 & 2
[C] Only 1, 2 & 3
[D] 1, 2, 3 & 4
Show Answer
Correct Answer: B [ Only 1 & 2]
Notes:
Both obey the laws of reflection.
Both obey the laws of refraction.
Both travel with the speed of 3 × 108 ms–1.
Ultraviolet waves get readily scattered as compared to visible light
Ultraviolet waves are chemically more active than visible light
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