NEET Physics Equation of Continuity Viscosity and Terminal Velocity MCQs

Question. As the temperature of a liquid is raised, the coefficient of viscosity
(a) decreases
(b) increases
(c) may increase or decrease depending on the nature of liquid
(d) remains the same

Answer: A

Question. After terminal velocity is reached, the acceleration of a body falling through a fluid is
(a) zero
(b) equal to g
(c) less than g
(d) greater than g

Answer: A

Question. Terminal velocity of ball depends on
(a) density difference of liquid and ball
(b) density of ball only
(c) density of liquid only
(d) area of the ball

Answer: A

Question.  A boat with base area 8m² floating on the surface of a still river is intended to move with a constant speed of 2 m/s by the application of a horizontal force. If the river bed is 2m deep find the force needed, (assuming a constant velocity gradient) Coefficient of viscosity of water is 0.90 × 10^–2 poise.
(a) 720 dyne
(b) 620 dyne
(c) 520 dyne
(d) 360 dyne

Answer: A

Question.  Which of the following statements is/are true?
I. Solid friction is independent of area of surface in contact and viscous drag is also independent of area of layers in contact.
II. Solid friction depends on the relative velocity of one body on the surface of another body while viscous drag is independent of the relative velocity between two layers of the liquid.
III. Solid friction is directly proportional to the normal reaction while viscosity is independent of the normal reaction between two layers of the liquid.
(a) III only
(b) II only
(c) I & II
(d) I, II & III

Answer: A

Question.  When a ball is released from rest in a very long column of viscous liquid, its downward acceleration is ‘a’ (just after release). Its acceleration when it has acquired two third of the maximum velocity is a/X. Find the value of X.
(a) 3
(b) 4
(c) 5
(d) 2

Answer: A

Question.  An air bubble of radius 1 cm rises with terminal velocity 0.21 cm/s in liquid column. If the density of liquid is 1.47 × 10³ kg/m³. Then the value of coefficient of viscosity of liquid ignoring the density of air, will be
(a) 1.52 × 10⁴ poise
(b) 1.82 × 10⁴ poise
(c) 1.78 × 10⁴ poise
(d) 1.71 × 10⁴ poise

Answer: A

Question. The relative velocity of two parallel layers of water is 8 cm/sec. If the perpendicular distance between the layers is 0.1 cm. Then velocity gradient will be
(a) 80/sec
(b) 60 /sec
(c) 50/sec
(d) 40/sec

Answer: A

Question. Assertion : Falling raindrops acquire a terminal velocity.
Reason : A constant force in the direction of motion and a velocity dependent force opposite to the direction of motion, always result in the acquisition of terminal velocity.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct.

Answer: A

Question. A liquid is filled upto a height of 20 cm in a cylindrical vessel. The speed of liquid coming out of a small hole at the bottom of the vessel is (g = 10 ms^–2)
(a) 2 ms^–1
(b) 3.2 ms^–1
(c) 1 ms^–1
(d) 1.2 ms^–1

Answer: A

Question. A solid ball of volume V experiences a viscous force F when falling with a speed v in a liquid. If another ball of volume 8 V with the same velocity v is allowed to fall in the same liquid, it experiences a force
(a) 2 F
(b) 4 F
(c) l6 F
(d) F

Answer: A

Question. A small spherical ball falling through a viscous medium of negligible density has terminal velocity v. Another ball of the same mass but of radius twice that of the earlier falling through the same viscous medium will have terminal velocity
(a) v/2
(b) 2v
(c) v/4
(d) v

Answer: A

Question. The velocity of water in a river is 18 km/hr near the surface. If the river is 5 m deep, find the shearing stress between the horizontal layers of water. The co-efficient of viscosity of water = 10^–2 poise
(a) 10^–2 N/m²
(b) 10^–4 N/m²
(c) 10^–1 N/m²
(d) 10^–3 N/m²

Answer: A