The rain drops falling from the sky neither injure us nor make holes on the ground because they move with

constant acceleration
variable acceleration
variable speed
constant terminal velocity

1 centipoise is equal to

1 kg m^-1 s^-1
1000 kg m^-1 s^-1
0.1 kg m^-1 s^-1
0.001 kg m^-1 s^-1

Solution

1 centipoise = 10^-2gcm^-1 s^-1= 0.001 kg m^-1s^-1

The lift of an air plane is based on

Torricelli's theorem
Bernoulli's theorem
Law of gravitation
conservation of linearmomentum

Solution

Apply Bernoulli’s theorem

Surface tension may be defined as

the work done per unit area in increasing the surfacearea of a liquid under isothermal condition
the work done per unit area in increasing the surface area of a liquid under the adiabatic condition
the work done per unit area in increasing the surface area of liquid under both isothermal and adiabatic condition
free surface energy per unit volume

Solution

In Isothermal conditons \(T=\frac{W}{\Delta A}\)
where, T = surface tension, W = work done,
ΔA = change in area.

Directions: Each question containsSTATEMENT-1 and STATEMENT-2. Choose the correct answer(ONLY ONE option is correct ) from the following-

Statement 1: The buoyant force on a submerged rigid objectcan be considered to be acting at the centre of mass of the object.

Statement 2 :For a rigid body a force field distributed uniformly through its volume can be considered to be acting at the centre of mass of the body.

(a)Statement -1 is false, Statement-2 is true
(b)Statement -1 is true, Statement-2 is true; Statement -2 is a correct explanation for Statement-1
(c)Statement -1 is true, Statement-2 is true; Statement-2 is not a correct explanation for Statement-1
(d)Statement -1 is true, Statement-2 is false

Solution

(d)Statement -1 is true, Statement-2 is false

Directions: Each question containsSTATEMENT-1 and STATEMENT-2. Choose the correct answer(ONLY ONE option is correct ) from the following-

Statement 1 : Falling raindrops acquire a terminal velocity.

Statement 2 :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)Statement -1 is false, Statement-2 is true
(b)Statement -1 is true, Statement-2 is true; Statement -2 is a correct explanation for Statement-1
(c)Statement -1 is true, Statement-2 is true; Statement-2 is not a correct explanation for Statement-1
(d)Statement -1 is true, Statement-2 is false

Solution

(a)Statement -1 is false, Statement-2 is true

Directions: Each question containsSTATEMENT-1 and STATEMENT-2. Choose the correct answer(ONLY ONE option is correct ) from the following-

Statement 1 :The velocity of flow of a liquid is smaller when pressure is larger and vice-versa.

Statement 2 :According to Bernoulli’s theorem, for the stream line flow of an ideal liquid, the total energy per unit mass remains constant.

(a)Statement -1 is false, Statement-2 is true
(b)Statement -1 is true, Statement-2 is true; Statement -2 is a correct explanation for Statement-1
(c)Statement -1 is true, Statement-2 is true; Statement-2 is not a correct explanation for Statement-1
(d)Statement -1 is true, Statement-2 is false

Solution

(a)Statement -1 is false, Statement-2 is true

Directions: Each question containsSTATEMENT-1 and STATEMENT-2. Choose the correct answer(ONLY ONE option is correct ) from the following-

Statement 1 : If a body is floating in a liquid, the density of liquid is always greater than the density of solid.

Statement 2 :Surface tension is the property of liquid surface.

(a)Statement -1 is false, Statement-2 is true
(b) Statement -1 is true, Statement-2 is true; Statement -2 is a correct explanation for Statement-1
(c)Statement -1 is true, Statement-2 is true; Statement-2 is not a correct explanation for Statement-1

Solution

(d) Statement -1 is true, Statement-2 is false

Directions: Each question containsSTATEMENT-1 and STATEMENT-2. Choose the correct answer(ONLY ONE option is correct ) from the following-

Statement 1: Smaller the droplets of water, spherical they are.

Statement 2 : Force of surface tension is equal,and opposite to force of gravity.

(a)Statement -1 is false, Statement-2 is true
(b)Statement -1 is true, Statement-2 is true; Statement -2 is a correct explanation for Statement-1
(c)Statement -1 is true, Statement-2 is true; Statement-2 is not a correct explanation for Statement-1
(d)Statement -1 is true, Statement-2 is false

Solution

(c)Statement -1 is true, Statement-2 is true; Statement-2 is not a correct explanation for Statement-1

Two glass plates are separated by water. If surface tension of water is 75 dyne/cm and area of each plate wetted by water is 8 cm² and the distance between the plates is 0.12mm, then the force applied to,separate the two plates is

10² dyne
10⁴ dyne
10⁵ dyne
10⁶ dyne

Solution

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