Mechanical Properties of Fluids Practice Questions - DPP for JEE

 Page 1


PART-I (Single Correct MCQs)
1. The cylindrical tube of a spray pump has radius, R, one end of which
has n fine holes, each of radius r. If the speed of the liquid in the tube is
V, the speed of the ejection of the liquid through the holes is :
(a)
(b)
(c)
(d)
2. On heating water, bubbles being formed at the bottom of the vessel
detach and rise. Take the bubbles to be spheres of radius R and making
a circular contact of radius r with the bottom of the vessel. If r < < R and
Page 2


PART-I (Single Correct MCQs)
1. The cylindrical tube of a spray pump has radius, R, one end of which
has n fine holes, each of radius r. If the speed of the liquid in the tube is
V, the speed of the ejection of the liquid through the holes is :
(a)
(b)
(c)
(d)
2. On heating water, bubbles being formed at the bottom of the vessel
detach and rise. Take the bubbles to be spheres of radius R and making
a circular contact of radius r with the bottom of the vessel. If r < < R and
the surface tension of water is T, value of r just
before bubbles detach is:  (density of water is ?
w
)
(a)
(b)
(c)
(d)
3. A jar is filled with two non-mixing liquids 1 and 2 having
densities ?
1 
and, ?
2 
respectively. A solid ball, made of a
material of density ?
3 
, is dropped in the jar. It comes to
equilibrium in the position shown in the figure.Which of the
following is true for ?
1
, ?
2
and ?
3
?
(a) ?
3 
< ?
1 
< ?
2
(b) ?
1 
> ?
3 
> ?
2
(c) ?
1 
< ?
2 
< ?
3
(d) ?
1 
< ?
3 
< ?
2
4. Figure shows a weigh-bridge, with a
beaker P with water on one pan and a
balancing weight R on the other. A solid
ball Q is hanging with a thread outside
water. It has volume 40 cm
3
 and weighs
80 g. If this solid is lowered to sink fully
in water, but not touching the beaker
anywhere, the balancing weight R’ will be
(a) same as R
(b) 40 g less than R
(c) 40 g more than R
(d) 80 g more than R
Page 3


PART-I (Single Correct MCQs)
1. The cylindrical tube of a spray pump has radius, R, one end of which
has n fine holes, each of radius r. If the speed of the liquid in the tube is
V, the speed of the ejection of the liquid through the holes is :
(a)
(b)
(c)
(d)
2. On heating water, bubbles being formed at the bottom of the vessel
detach and rise. Take the bubbles to be spheres of radius R and making
a circular contact of radius r with the bottom of the vessel. If r < < R and
the surface tension of water is T, value of r just
before bubbles detach is:  (density of water is ?
w
)
(a)
(b)
(c)
(d)
3. A jar is filled with two non-mixing liquids 1 and 2 having
densities ?
1 
and, ?
2 
respectively. A solid ball, made of a
material of density ?
3 
, is dropped in the jar. It comes to
equilibrium in the position shown in the figure.Which of the
following is true for ?
1
, ?
2
and ?
3
?
(a) ?
3 
< ?
1 
< ?
2
(b) ?
1 
> ?
3 
> ?
2
(c) ?
1 
< ?
2 
< ?
3
(d) ?
1 
< ?
3 
< ?
2
4. Figure shows a weigh-bridge, with a
beaker P with water on one pan and a
balancing weight R on the other. A solid
ball Q is hanging with a thread outside
water. It has volume 40 cm
3
 and weighs
80 g. If this solid is lowered to sink fully
in water, but not touching the beaker
anywhere, the balancing weight R’ will be
(a) same as R
(b) 40 g less than R
(c) 40 g more than R
(d) 80 g more than R
5. Let T
1
 be surface tension between solid and air, T
2
 be the surface
tension between solid and liquid and T be the surface tension between
liquid and air. Then in equilibrium, for a drop of liquid on a clean glass
plate, the correct relation is (? is angle of contact)
(a) cos ? = 
(b) cos ? = 
(c) cos ? = 
(d) cos ? = 
6. A spherical solid ball of volume V is made of a material of density ?
1
. It
is falling through a liquid of density ?
1 
(?
2
< ?
1
). Assume that the liquid
applies a viscous force on the ball that is proportional to the square of
its speed v, i.e., F
viscous
 = –kv
2
 (k > 0). The terminal speed of the ball is
(a)
(b)
(c) 
(d)
7. A square hole of side length l is made at a depth of h and a circular
hole of radius r is made at a depth of 4h from the surface of water in a
water tank kept on a horizontal surface. If l << h, r << h and the rate
of water flow from the holes is the same, then r is equal to
Page 4


PART-I (Single Correct MCQs)
1. The cylindrical tube of a spray pump has radius, R, one end of which
has n fine holes, each of radius r. If the speed of the liquid in the tube is
V, the speed of the ejection of the liquid through the holes is :
(a)
(b)
(c)
(d)
2. On heating water, bubbles being formed at the bottom of the vessel
detach and rise. Take the bubbles to be spheres of radius R and making
a circular contact of radius r with the bottom of the vessel. If r < < R and
the surface tension of water is T, value of r just
before bubbles detach is:  (density of water is ?
w
)
(a)
(b)
(c)
(d)
3. A jar is filled with two non-mixing liquids 1 and 2 having
densities ?
1 
and, ?
2 
respectively. A solid ball, made of a
material of density ?
3 
, is dropped in the jar. It comes to
equilibrium in the position shown in the figure.Which of the
following is true for ?
1
, ?
2
and ?
3
?
(a) ?
3 
< ?
1 
< ?
2
(b) ?
1 
> ?
3 
> ?
2
(c) ?
1 
< ?
2 
< ?
3
(d) ?
1 
< ?
3 
< ?
2
4. Figure shows a weigh-bridge, with a
beaker P with water on one pan and a
balancing weight R on the other. A solid
ball Q is hanging with a thread outside
water. It has volume 40 cm
3
 and weighs
80 g. If this solid is lowered to sink fully
in water, but not touching the beaker
anywhere, the balancing weight R’ will be
(a) same as R
(b) 40 g less than R
(c) 40 g more than R
(d) 80 g more than R
5. Let T
1
 be surface tension between solid and air, T
2
 be the surface
tension between solid and liquid and T be the surface tension between
liquid and air. Then in equilibrium, for a drop of liquid on a clean glass
plate, the correct relation is (? is angle of contact)
(a) cos ? = 
(b) cos ? = 
(c) cos ? = 
(d) cos ? = 
6. A spherical solid ball of volume V is made of a material of density ?
1
. It
is falling through a liquid of density ?
1 
(?
2
< ?
1
). Assume that the liquid
applies a viscous force on the ball that is proportional to the square of
its speed v, i.e., F
viscous
 = –kv
2
 (k > 0). The terminal speed of the ball is
(a)
(b)
(c) 
(d)
7. A square hole of side length l is made at a depth of h and a circular
hole of radius r is made at a depth of 4h from the surface of water in a
water tank kept on a horizontal surface. If l << h, r << h and the rate
of water flow from the holes is the same, then r is equal to
(a)
(b)
(c)
(d)
8. A glass tube of uniform internal radius (r) has a
valve separating the two identical ends. Initially,
the valve is in a tightly closed position.
End 1 has a hemispherical soap bubble of radius r.
End 2 has sub-hemispherical soap bubble (figure). Just after opening the
valve
(a) air from end 1 flows towards end 2. No change in the volume of the soap
bubbles
(b) air from end 1 flows towards end 2. Volume of the soap bubble at end 1
decreases
(c) no change occurs
(d) air from end 2 flows towards end 1. Volume of the soap bubble at end 1
increases
9. A ball of radius r and density  falls freely under gravity
through a distance h before entering water. Velocity of ball 
does not change even on entering water. If viscosity of water
is  the value of h is given by
(a)
(b)
(c)
(d)
Page 5


PART-I (Single Correct MCQs)
1. The cylindrical tube of a spray pump has radius, R, one end of which
has n fine holes, each of radius r. If the speed of the liquid in the tube is
V, the speed of the ejection of the liquid through the holes is :
(a)
(b)
(c)
(d)
2. On heating water, bubbles being formed at the bottom of the vessel
detach and rise. Take the bubbles to be spheres of radius R and making
a circular contact of radius r with the bottom of the vessel. If r < < R and
the surface tension of water is T, value of r just
before bubbles detach is:  (density of water is ?
w
)
(a)
(b)
(c)
(d)
3. A jar is filled with two non-mixing liquids 1 and 2 having
densities ?
1 
and, ?
2 
respectively. A solid ball, made of a
material of density ?
3 
, is dropped in the jar. It comes to
equilibrium in the position shown in the figure.Which of the
following is true for ?
1
, ?
2
and ?
3
?
(a) ?
3 
< ?
1 
< ?
2
(b) ?
1 
> ?
3 
> ?
2
(c) ?
1 
< ?
2 
< ?
3
(d) ?
1 
< ?
3 
< ?
2
4. Figure shows a weigh-bridge, with a
beaker P with water on one pan and a
balancing weight R on the other. A solid
ball Q is hanging with a thread outside
water. It has volume 40 cm
3
 and weighs
80 g. If this solid is lowered to sink fully
in water, but not touching the beaker
anywhere, the balancing weight R’ will be
(a) same as R
(b) 40 g less than R
(c) 40 g more than R
(d) 80 g more than R
5. Let T
1
 be surface tension between solid and air, T
2
 be the surface
tension between solid and liquid and T be the surface tension between
liquid and air. Then in equilibrium, for a drop of liquid on a clean glass
plate, the correct relation is (? is angle of contact)
(a) cos ? = 
(b) cos ? = 
(c) cos ? = 
(d) cos ? = 
6. A spherical solid ball of volume V is made of a material of density ?
1
. It
is falling through a liquid of density ?
1 
(?
2
< ?
1
). Assume that the liquid
applies a viscous force on the ball that is proportional to the square of
its speed v, i.e., F
viscous
 = –kv
2
 (k > 0). The terminal speed of the ball is
(a)
(b)
(c) 
(d)
7. A square hole of side length l is made at a depth of h and a circular
hole of radius r is made at a depth of 4h from the surface of water in a
water tank kept on a horizontal surface. If l << h, r << h and the rate
of water flow from the holes is the same, then r is equal to
(a)
(b)
(c)
(d)
8. A glass tube of uniform internal radius (r) has a
valve separating the two identical ends. Initially,
the valve is in a tightly closed position.
End 1 has a hemispherical soap bubble of radius r.
End 2 has sub-hemispherical soap bubble (figure). Just after opening the
valve
(a) air from end 1 flows towards end 2. No change in the volume of the soap
bubbles
(b) air from end 1 flows towards end 2. Volume of the soap bubble at end 1
decreases
(c) no change occurs
(d) air from end 2 flows towards end 1. Volume of the soap bubble at end 1
increases
9. A ball of radius r and density  falls freely under gravity
through a distance h before entering water. Velocity of ball 
does not change even on entering water. If viscosity of water
is  the value of h is given by
(a)
(b)
(c)
(d)
10. Two capillary of length L and 2L and of radius R and 2R are connected
in series. The net rate of flow of fluid through them will be (given rate
to the flow through single capillary, X = )
(a)
(b)
(c)
(d)
11. A tank is filled with water upto a height H.
Water is allowed to come out of a hole P in one
of the walls at a depth h below the surface of
water (see fig.) Express the horizontal distance X
in terms of H and h.
(a)
(b)
(c)
(d)
12. A thread is tied slightly loose to a wire frame as in
figure and the frame is dipped into a soap solution
and taken out. The frame is completely covered with
the film. When the portion A is punctured  with a
pin, the thread
(a) becomes concave towards A
(b) becomes convex towards A
(c) remains in the initial position
(d) either (a)  or (b) depending