Physics (CDS-Solved Paper)

Total Questions: 50

11. People prefer to wear cotton clothes in summer season. This is due to the fact that cotton clothes are [Evening Shift-2019 (II)]

Correct Answer: (a) good absorbers of water
Solution:

People prefer to wear cotton clothes in summer season to keep them cool and comfortable. In summer, we sweat more, cotton being a good absorber of water helps in absorbing the sweat and exposes it to the atmosphere for evaporation. So, we can say that cotton clothes are good absorbers of water.

12. Two identical solid pieces, one of gold and other of silver, when immersed completely in water exhibit equal weights. When weighed in air (given that, density of gold is greater than that of silver), [Morning Shift-2019 (I)]

Correct Answer: (c) Both silver and gold pieces weigh equal
Solution:

Since, gold is more denser than silver. But it is given that both pieces have identical and equal weight in water, it means both have equal volume and mass. (May be gold piece hollow inside.) (As we know, force of gravity is determined by mass and buoyant force is determined by volume) So, both silver and gold pieces weight equal in air.

13. Solve the following question? [Morning Shift-2019 (I)]


Correct Answer: (d)
Solution:

As we know that, infrared light has a lower frequency than visible light and visible light has a lower frequency than ultraviolet light.
Since, wavelength of a light is inversely proportional to its frequency, therefore

14. An electron and a proton starting from rest get accelerated through potential difference of 100 kV. The final speeds of the electron and the proton are vₑ and vₚ, respectively. Which one of the following relation is correct? [Morning Shift-2019 (I)]

Correct Answer: (a) vₑ < vₚ
Solution:

15. If two vectors A and B are at an angle θ ≠ ° 0 , then [Morning Shift-2019 (I)]

Correct Answer: (b) |A| + |B| > |A + B|
Solution:

Since, any one side of a triangle is less than the sum of the other two sides individually, so for any two vectors A and B,

16. The Hooke’s law is valid for [Morning Shift-2019 (I)]

Correct Answer: (a) only proportional region of the stress-strain curve
Solution:

Hooke’s law is valid for only proportional region of the stress- strain curve. Q Hooke’s law → stress ∝ strain

17. A particle moves with uniform acceleration along a straight line from rest. The percentage increase in displacement during 6th compared to that in 5th is about [Morning Shift-2019 (I)]

Correct Answer: (b) 22%
Solution:

The particle is moving with uniform acceleration along a straight line from rest. Displacement during 6th second,

18. If two miscible liquids of same volume but different densities ρ₁ and ρ₂ are mixed, then the density of the mixture is given by [Morning Shift-2019 (I)]

Correct Answer: (b)
Solution:

19. Solve the following question ? [Morning Shift-2019 (I)]

Correct Answer: (d) on xy -plane and along x-direction
Solution:

20. Two persons are holding a rope of negligible mass horizontally. A 20 kg mass is attached to the rope at the mid-point, as a result, the rope deviates from the horizontal direction. The tension required to completely straighten the rope is (g = 10 m/s²)

Correct Answer: (a) 200 N
Solution:

Given, m = 20 kg
Tension required to completely straighten the rope.
From Newton’s second law of motion,
F = ma
F = 20 × 10 (∵ acceleration a due to gravity g = 10 m/s²)
= 200 N