Mechanical Properties of Fluids: JEE Mains Previous Year Questions (2021-2024) | Physics for JEE Main & Advanced PDF Download

 Page 1


Previous Year Questions (2021-24): 
Mechanical Properties of Fluids 
2024 
Q1 - 2024 (01 Feb Shift 1) 
A plane is in level flight at constant speed and each of its two wings has an area 
of 40 m
2
. If the speed of the air is 180 km / h over the lower wing surface and 
252 km / h over the upper wing surface, the mass of the plane is kg. (Take air 
density to be 1 kg m
- 3
 and g = 10 ms
- 2
 ) 
Q2 - 2024 (01 Feb Shift 2) 
A big drop is formed by coalescing 1000 small droplets of water. The surface 
energy will become : 
(1) 100 times 
(2) 10 times 
(3) 
1
100
 th 
(4) 
1
10
 th 
Q3 - 2024 (27 Jan Shift 1) 
Given below are two statements : 
Statement (I) :Viscosity of gases is greater than that of liquids. 
Statement (II) : Surface tension of a liquid decreases due to the presence of 
insoluble impurities. 
In the light of the above statements, choose the most appropriate answer from 
the options given below: 
(1) Statement I is correct but statement II is incorrect 
(2) Statement I is incorrect but Statement II is correct 
(3) Both Statement I and Statement II are incorrect 
(4) Both Statement I and Statement II are correct 
Page 2


Previous Year Questions (2021-24): 
Mechanical Properties of Fluids 
2024 
Q1 - 2024 (01 Feb Shift 1) 
A plane is in level flight at constant speed and each of its two wings has an area 
of 40 m
2
. If the speed of the air is 180 km / h over the lower wing surface and 
252 km / h over the upper wing surface, the mass of the plane is kg. (Take air 
density to be 1 kg m
- 3
 and g = 10 ms
- 2
 ) 
Q2 - 2024 (01 Feb Shift 2) 
A big drop is formed by coalescing 1000 small droplets of water. The surface 
energy will become : 
(1) 100 times 
(2) 10 times 
(3) 
1
100
 th 
(4) 
1
10
 th 
Q3 - 2024 (27 Jan Shift 1) 
Given below are two statements : 
Statement (I) :Viscosity of gases is greater than that of liquids. 
Statement (II) : Surface tension of a liquid decreases due to the presence of 
insoluble impurities. 
In the light of the above statements, choose the most appropriate answer from 
the options given below: 
(1) Statement I is correct but statement II is incorrect 
(2) Statement I is incorrect but Statement II is correct 
(3) Both Statement I and Statement II are incorrect 
(4) Both Statement I and Statement II are correct 
Q4 - 2024 (27 Jan Shift 2) 
The reading of pressure metre attached with a closed pipe is 4 . 5 × 10
4
 N / m
2
. On 
opening the valve, water starts flowing and the reading of pressure metre falls to 
2 . 0 × 10
4
 N / m
2
. The velocity of water is found to be v V m / s. The value of V is 
Q5 - 2024 (29 Jan Shift 1) 
Given below are two statements: 
Statement I : If a capillary tube is immersed first in cold water and then in hot 
water, the height of capillary rise will be smaller in hot water. 
Statement II : If a capillary tube is immersed first in cold water and then in hot 
water, the height of capillary rise will be smaller in cold water. 
In the light of the above statements, choose the most appropriate from the 
options given below 
(1) Both Statement I and Statement II are true 
(2) Both Statement I and Statement II are false 
(3) Statement I is true but Statement II is false 
(4) Statement I is false but Statement II is true 
Q6 - 2024 (29 Jan Shift 1) 
In a test experiment on a model aeroplane in wind tunnel, the flow speeds on the 
upper and lower surfaces of the wings are 70 ms
- 1
 and 65 ms
- 1
 respectively. If 
the wing area is 2 m
2
 the lift of the wing is N. 
(Given density of air = 1 . 2 kg m
- 3
 ) 
Q7 - 2024 (29 Jan Shift 2) 
A small liquid drop of radius R is divided into 27 identical liquid drops. If the 
surface tension is T, then the work done in the process will be : 
(1) 8 ?? ?? 2
 T 
(2) 3 ?? ?? 2
 T 
(3) 
1
8
?? ?? 2
?? 
(4) 4 ?? ?? 2
 T 
Page 3


Previous Year Questions (2021-24): 
Mechanical Properties of Fluids 
2024 
Q1 - 2024 (01 Feb Shift 1) 
A plane is in level flight at constant speed and each of its two wings has an area 
of 40 m
2
. If the speed of the air is 180 km / h over the lower wing surface and 
252 km / h over the upper wing surface, the mass of the plane is kg. (Take air 
density to be 1 kg m
- 3
 and g = 10 ms
- 2
 ) 
Q2 - 2024 (01 Feb Shift 2) 
A big drop is formed by coalescing 1000 small droplets of water. The surface 
energy will become : 
(1) 100 times 
(2) 10 times 
(3) 
1
100
 th 
(4) 
1
10
 th 
Q3 - 2024 (27 Jan Shift 1) 
Given below are two statements : 
Statement (I) :Viscosity of gases is greater than that of liquids. 
Statement (II) : Surface tension of a liquid decreases due to the presence of 
insoluble impurities. 
In the light of the above statements, choose the most appropriate answer from 
the options given below: 
(1) Statement I is correct but statement II is incorrect 
(2) Statement I is incorrect but Statement II is correct 
(3) Both Statement I and Statement II are incorrect 
(4) Both Statement I and Statement II are correct 
Q4 - 2024 (27 Jan Shift 2) 
The reading of pressure metre attached with a closed pipe is 4 . 5 × 10
4
 N / m
2
. On 
opening the valve, water starts flowing and the reading of pressure metre falls to 
2 . 0 × 10
4
 N / m
2
. The velocity of water is found to be v V m / s. The value of V is 
Q5 - 2024 (29 Jan Shift 1) 
Given below are two statements: 
Statement I : If a capillary tube is immersed first in cold water and then in hot 
water, the height of capillary rise will be smaller in hot water. 
Statement II : If a capillary tube is immersed first in cold water and then in hot 
water, the height of capillary rise will be smaller in cold water. 
In the light of the above statements, choose the most appropriate from the 
options given below 
(1) Both Statement I and Statement II are true 
(2) Both Statement I and Statement II are false 
(3) Statement I is true but Statement II is false 
(4) Statement I is false but Statement II is true 
Q6 - 2024 (29 Jan Shift 1) 
In a test experiment on a model aeroplane in wind tunnel, the flow speeds on the 
upper and lower surfaces of the wings are 70 ms
- 1
 and 65 ms
- 1
 respectively. If 
the wing area is 2 m
2
 the lift of the wing is N. 
(Given density of air = 1 . 2 kg m
- 3
 ) 
Q7 - 2024 (29 Jan Shift 2) 
A small liquid drop of radius R is divided into 27 identical liquid drops. If the 
surface tension is T, then the work done in the process will be : 
(1) 8 ?? ?? 2
 T 
(2) 3 ?? ?? 2
 T 
(3) 
1
8
?? ?? 2
?? 
(4) 4 ?? ?? 2
 T 
Q8 - 2024 (30 Jan Shift 2) 
A big drop is formed by coalescing 1000 small identical drops of water. If ?? 1
 be 
the total surface energy of 1000 small drops of water and ?? 2
 be the surface 
energy of single big drop of water, the ?? 1
: ?? 2
 is x : 1 where x = 
Q9 - 2024 (31 Jan Shift 2) 
A small spherical ball of radius ?? , falling through a viscous medium of negligible 
density has terminal velocity ' v '. Another ball of the same mass but of radius 2r, 
falling through the same viscous medium will have terminal velocity: 
(1) 
v
2
 
(2) 
v
4
 
(3) 4 ?? 
(4) 2 ?? 
Answer Key 
 
Solutions 
Q1 
A = 80 m
2
 
Using Bernonlli equation 
A ( P
2
- P
1
) =
1
2
?? ( V
1
2
- V
2
2
) A 
mg =
1
2
× 1 ( 70
2
- 50
2
) × 80 
mg = 40 × 2400 
m = 9600 kg 
Page 4


Previous Year Questions (2021-24): 
Mechanical Properties of Fluids 
2024 
Q1 - 2024 (01 Feb Shift 1) 
A plane is in level flight at constant speed and each of its two wings has an area 
of 40 m
2
. If the speed of the air is 180 km / h over the lower wing surface and 
252 km / h over the upper wing surface, the mass of the plane is kg. (Take air 
density to be 1 kg m
- 3
 and g = 10 ms
- 2
 ) 
Q2 - 2024 (01 Feb Shift 2) 
A big drop is formed by coalescing 1000 small droplets of water. The surface 
energy will become : 
(1) 100 times 
(2) 10 times 
(3) 
1
100
 th 
(4) 
1
10
 th 
Q3 - 2024 (27 Jan Shift 1) 
Given below are two statements : 
Statement (I) :Viscosity of gases is greater than that of liquids. 
Statement (II) : Surface tension of a liquid decreases due to the presence of 
insoluble impurities. 
In the light of the above statements, choose the most appropriate answer from 
the options given below: 
(1) Statement I is correct but statement II is incorrect 
(2) Statement I is incorrect but Statement II is correct 
(3) Both Statement I and Statement II are incorrect 
(4) Both Statement I and Statement II are correct 
Q4 - 2024 (27 Jan Shift 2) 
The reading of pressure metre attached with a closed pipe is 4 . 5 × 10
4
 N / m
2
. On 
opening the valve, water starts flowing and the reading of pressure metre falls to 
2 . 0 × 10
4
 N / m
2
. The velocity of water is found to be v V m / s. The value of V is 
Q5 - 2024 (29 Jan Shift 1) 
Given below are two statements: 
Statement I : If a capillary tube is immersed first in cold water and then in hot 
water, the height of capillary rise will be smaller in hot water. 
Statement II : If a capillary tube is immersed first in cold water and then in hot 
water, the height of capillary rise will be smaller in cold water. 
In the light of the above statements, choose the most appropriate from the 
options given below 
(1) Both Statement I and Statement II are true 
(2) Both Statement I and Statement II are false 
(3) Statement I is true but Statement II is false 
(4) Statement I is false but Statement II is true 
Q6 - 2024 (29 Jan Shift 1) 
In a test experiment on a model aeroplane in wind tunnel, the flow speeds on the 
upper and lower surfaces of the wings are 70 ms
- 1
 and 65 ms
- 1
 respectively. If 
the wing area is 2 m
2
 the lift of the wing is N. 
(Given density of air = 1 . 2 kg m
- 3
 ) 
Q7 - 2024 (29 Jan Shift 2) 
A small liquid drop of radius R is divided into 27 identical liquid drops. If the 
surface tension is T, then the work done in the process will be : 
(1) 8 ?? ?? 2
 T 
(2) 3 ?? ?? 2
 T 
(3) 
1
8
?? ?? 2
?? 
(4) 4 ?? ?? 2
 T 
Q8 - 2024 (30 Jan Shift 2) 
A big drop is formed by coalescing 1000 small identical drops of water. If ?? 1
 be 
the total surface energy of 1000 small drops of water and ?? 2
 be the surface 
energy of single big drop of water, the ?? 1
: ?? 2
 is x : 1 where x = 
Q9 - 2024 (31 Jan Shift 2) 
A small spherical ball of radius ?? , falling through a viscous medium of negligible 
density has terminal velocity ' v '. Another ball of the same mass but of radius 2r, 
falling through the same viscous medium will have terminal velocity: 
(1) 
v
2
 
(2) 
v
4
 
(3) 4 ?? 
(4) 2 ?? 
Answer Key 
 
Solutions 
Q1 
A = 80 m
2
 
Using Bernonlli equation 
A ( P
2
- P
1
) =
1
2
?? ( V
1
2
- V
2
2
) A 
mg =
1
2
× 1 ( 70
2
- 50
2
) × 80 
mg = 40 × 2400 
m = 9600 kg 
Q2 
Lets say radius of small droplets is r and that of big drop is R 
4
3
?? R
3
= 1000
4
3
?? r
3
 
R = 10r 
U
i
= 1000 ( 4 ?? r
2
 S ) 
U
f
= 4 ?? R
2
 S 
= 100 ( 4 ?? r
2
 S ) 
U
f
=
1
10
U
i
 
Q3 
Gases have less viscosity. 
Due to insoluble impurities like detergent surface tension decreases 
Q4 
Change in pressure =
1
2
?? v
2
 
4 . 5 × 10
4
- 2 . 0 × 10
4
=
1
2
× 10
3
× v
2
 
2 . 5 × 10
4
=
1
2
× 10
3
× v
2
 
v
2
= 50 
v = v 50 
Velocity of water = v V = v 50 
= V = 50 
Q5 
Surface tension will be less as temperature increases 
h =
2 T co s ? ?? ?? gr
 
Page 5


Previous Year Questions (2021-24): 
Mechanical Properties of Fluids 
2024 
Q1 - 2024 (01 Feb Shift 1) 
A plane is in level flight at constant speed and each of its two wings has an area 
of 40 m
2
. If the speed of the air is 180 km / h over the lower wing surface and 
252 km / h over the upper wing surface, the mass of the plane is kg. (Take air 
density to be 1 kg m
- 3
 and g = 10 ms
- 2
 ) 
Q2 - 2024 (01 Feb Shift 2) 
A big drop is formed by coalescing 1000 small droplets of water. The surface 
energy will become : 
(1) 100 times 
(2) 10 times 
(3) 
1
100
 th 
(4) 
1
10
 th 
Q3 - 2024 (27 Jan Shift 1) 
Given below are two statements : 
Statement (I) :Viscosity of gases is greater than that of liquids. 
Statement (II) : Surface tension of a liquid decreases due to the presence of 
insoluble impurities. 
In the light of the above statements, choose the most appropriate answer from 
the options given below: 
(1) Statement I is correct but statement II is incorrect 
(2) Statement I is incorrect but Statement II is correct 
(3) Both Statement I and Statement II are incorrect 
(4) Both Statement I and Statement II are correct 
Q4 - 2024 (27 Jan Shift 2) 
The reading of pressure metre attached with a closed pipe is 4 . 5 × 10
4
 N / m
2
. On 
opening the valve, water starts flowing and the reading of pressure metre falls to 
2 . 0 × 10
4
 N / m
2
. The velocity of water is found to be v V m / s. The value of V is 
Q5 - 2024 (29 Jan Shift 1) 
Given below are two statements: 
Statement I : If a capillary tube is immersed first in cold water and then in hot 
water, the height of capillary rise will be smaller in hot water. 
Statement II : If a capillary tube is immersed first in cold water and then in hot 
water, the height of capillary rise will be smaller in cold water. 
In the light of the above statements, choose the most appropriate from the 
options given below 
(1) Both Statement I and Statement II are true 
(2) Both Statement I and Statement II are false 
(3) Statement I is true but Statement II is false 
(4) Statement I is false but Statement II is true 
Q6 - 2024 (29 Jan Shift 1) 
In a test experiment on a model aeroplane in wind tunnel, the flow speeds on the 
upper and lower surfaces of the wings are 70 ms
- 1
 and 65 ms
- 1
 respectively. If 
the wing area is 2 m
2
 the lift of the wing is N. 
(Given density of air = 1 . 2 kg m
- 3
 ) 
Q7 - 2024 (29 Jan Shift 2) 
A small liquid drop of radius R is divided into 27 identical liquid drops. If the 
surface tension is T, then the work done in the process will be : 
(1) 8 ?? ?? 2
 T 
(2) 3 ?? ?? 2
 T 
(3) 
1
8
?? ?? 2
?? 
(4) 4 ?? ?? 2
 T 
Q8 - 2024 (30 Jan Shift 2) 
A big drop is formed by coalescing 1000 small identical drops of water. If ?? 1
 be 
the total surface energy of 1000 small drops of water and ?? 2
 be the surface 
energy of single big drop of water, the ?? 1
: ?? 2
 is x : 1 where x = 
Q9 - 2024 (31 Jan Shift 2) 
A small spherical ball of radius ?? , falling through a viscous medium of negligible 
density has terminal velocity ' v '. Another ball of the same mass but of radius 2r, 
falling through the same viscous medium will have terminal velocity: 
(1) 
v
2
 
(2) 
v
4
 
(3) 4 ?? 
(4) 2 ?? 
Answer Key 
 
Solutions 
Q1 
A = 80 m
2
 
Using Bernonlli equation 
A ( P
2
- P
1
) =
1
2
?? ( V
1
2
- V
2
2
) A 
mg =
1
2
× 1 ( 70
2
- 50
2
) × 80 
mg = 40 × 2400 
m = 9600 kg 
Q2 
Lets say radius of small droplets is r and that of big drop is R 
4
3
?? R
3
= 1000
4
3
?? r
3
 
R = 10r 
U
i
= 1000 ( 4 ?? r
2
 S ) 
U
f
= 4 ?? R
2
 S 
= 100 ( 4 ?? r
2
 S ) 
U
f
=
1
10
U
i
 
Q3 
Gases have less viscosity. 
Due to insoluble impurities like detergent surface tension decreases 
Q4 
Change in pressure =
1
2
?? v
2
 
4 . 5 × 10
4
- 2 . 0 × 10
4
=
1
2
× 10
3
× v
2
 
2 . 5 × 10
4
=
1
2
× 10
3
× v
2
 
v
2
= 50 
v = v 50 
Velocity of water = v V = v 50 
= V = 50 
Q5 
Surface tension will be less as temperature increases 
h =
2 T co s ? ?? ?? gr
 
Height of capillary rise will be smaller in hot water and larger in cold water. 
Q6 
F =
1
2
?? ( v
1
2
- v
2
2
) A 
F =
1
2
× 1 . 2 × ( 70
2
+ 65
2
) × 2 
= 810 N 
Q7 
Volume constant 
4
3
?? ?? 3
= 27 ×
4
3
× ?? ?? 3
 
?? 3
= 27 ?? 3
 
?? = 3 ?? 
?? =
?? 3
 
?? 2
=
?? 2
9
 
Work done = T · ? A 
= 27 T ( 4 ?? r
2
) - T4 ?? R
2
 
= 27 T4 ?? R
2
9
- 4 ?? R
2
 T 
= 8 ?? R
2
 T 
Q8 
?? ( ?
3
4
?? ?? 3
) 1 0 0 0 = ?
3
4
?? ?? 3
?? 
?? = 10 ?? 
?? 1
= 1000 × 4 ?? ?? 2
× ?? 
?? 2
= 4 ?? ( 10 ?? )
2
?? 
?? 1
?? 2
=
10
1
, ?? = 10