Fluid Statics and Dynamics MCQs

Question 1

Water moves at 0.6 m/s in a pipe of diameter 10 cm, which narrows to 5 cm. The speed in the narrow part is:

Accepted Answer

2.4 m/s

Answer

2.5 m/s

Answer

1.2 m/s

Answer

4.8 m/s

Question 2

A ship of mass 5 10^6 kg floats in sea water (density 1025 kg/m^3). The volume of water it displaces is about:

Accepted Answer

4880 m^3

Answer

5.1 10^9 m^3

Answer

5000 m^3

Answer

205 m^3

Question 3

A block of density 7800 kg/m^3 floats in a liquid of density 13600 kg/m^3. The fraction of its volume below the surface is:

Accepted Answer

0.574

Answer

0.426

Answer

0.287

Answer

1.74

Question 4

Each term in Bernoulli's equation has the unit of:

Accepted Answer

pressure (energy per unit volume)

Answer

force

Answer

velocity

Answer

energy

Question 5

A block of density 600 kg/m^3 floats in a liquid of density 1000 kg/m^3. The fraction of its volume below the surface is:

Accepted Answer

0.6

Answer

1.67

Answer

0.3

Answer

0.4

Question 6

A fluid of density 1000 kg/m^3 flows at 5 m/s through a pipe of area 4 10^-4 m^2. The mass flow rate is:

Accepted Answer

2 kg/s

Answer

20 kg/s

Answer

4 kg/s

Answer

0.2 kg/s

Question 7

Water (rho = 1000 kg/m^3) flows horizontally. At one point P = 2 10^5 Pa and v = 2 m/s; at another v = 6 m/s. The pressure there is:

Accepted Answer

1.84 10^5 Pa

Answer

92,000 Pa

Answer

1.84 10^6 Pa

Answer

3.68 10^5 Pa

Question 8

Chimneys draw smoke up better on windy days partly because:

Accepted Answer

wind across the top lowers the pressure there

Answer

wind pushes smoke down

Answer

smoke is heavier

Answer

the fire gets colder

Question 9

A steel ship floats although steel is denser than water because:

Accepted Answer

its hollow shape displaces a large volume of water

Answer

steel becomes lighter in sea water

Answer

the engine holds it up

Answer

it is pushed by the waves

Question 10

Water leaks through a small hole 1.8 m below the surface of an open tank. The speed of efflux is (g = 9.8):

Accepted Answer

5.94 m/s

Answer

8.4 m/s

Answer

2.97 m/s

Answer

11.9 m/s

Question 11

If a pipe's radius is halved, the fluid speed becomes:

Accepted Answer

4 times as large

Answer

unchanged

Answer

half

Answer

2 times as large

Question 12

A body of volume 0.5 m^3 is fully immersed in a liquid of density 1000 kg/m^3. The upthrust on it is (g = 9.8):

Accepted Answer

4900 N

Answer

49,000 N

Answer

9800 N

Answer

490 N

Question 13

A small steel ball dropped into glycerine first accelerates and then:

Accepted Answer

moves at constant (terminal) velocity

Answer

keeps accelerating

Answer

rises

Answer

stops

Question 14

A stream of honey falling from a spoon gets thinner as it falls because:

Accepted Answer

its speed increases, so its cross-section must decrease

Answer

air pushes it inward

Answer

honey evaporates

Answer

honey becomes denser

Question 15

Which is closest to an ideal fluid?

Accepted Answer

water flowing slowly

Answer

honey

Answer

thick tar

Answer

air in a storm

Question 16

Blood is a viscous fluid, so the heart must:

Accepted Answer

do work to keep it flowing through the vessels

Answer

only pump it once

Answer

do no work

Answer

make it compressible

Question 17

Using Stokes' law, the drag on a sphere of radius 0.002 m moving at 0.01 m/s through a fluid of viscosity 1.5 Pa s is:

Accepted Answer

5.65 10^-4 N

Answer

3 10^-5 N

Answer

2.83 10^-4 N

Answer

0.00113 N

Question 18

Water (rho = 1000 kg/m^3) flows horizontally. At one point P = 3 10^5 Pa and v = 3 m/s; at another v = 9 m/s. The pressure there is:

Accepted Answer

2.64 10^5 Pa

Answer

5.28 10^5 Pa

Answer

2.64 10^6 Pa

Answer

1.32 10^5 Pa

Question 19

A body of volume 0.01 m^3 is fully immersed in a liquid of density 800 kg/m^3. The upthrust on it is (g = 9.8):

Accepted Answer

78.4 N

Answer

784 N

Answer

7.84 N

Answer

157 N

Question 20

The weight of water displaced by a ship is called its:

Accepted Answer

displacement

Answer

draught

Answer

freeboard

Answer

tonnage of steel

Question 21

As the temperature of a gas rises, its viscosity:

Accepted Answer

increases

Answer

becomes zero

Answer

decreases

Answer

stays the same

Question 22

A non-viscous fluid is one with:

Accepted Answer

no internal friction between its layers

Answer

turbulent flow

Answer

very high density

Answer

no weight

Question 23

Non-viscous flow implies that:

Accepted Answer

no energy is lost to internal friction

Answer

the fluid can't move

Answer

pressure is constant

Answer

the fluid is solid

Question 24

Why can't fluid accumulate between two sections of a rigid pipe in steady flow of an incompressible fluid?

Accepted Answer

the volume between them is fixed and the fluid can't be squashed

Answer

the fluid evaporates

Answer

the pipe stretches

Answer

gravity removes it

Question 25

Because of viscosity, a real fluid flowing through a pipe:

Accepted Answer

loses some mechanical energy as heat

Answer

has zero pressure drop

Answer

speeds up without a pump

Answer

gains energy

Fluid Statics and Dynamics MCQs — Physics (page 6)

126. Water moves at 0.6 m/s in a pipe of diameter 10 cm, which narrows to 5 cm. The speed in the narrow part is:

127. A ship of mass 5 10^6 kg floats in sea water (density 1025 kg/m^3). The volume of water it displaces is about:

128. A block of density 7800 kg/m^3 floats in a liquid of density 13600 kg/m^3. The fraction of its volume below the surface is:

129. Each term in Bernoulli's equation has the unit of:

130. A block of density 600 kg/m^3 floats in a liquid of density 1000 kg/m^3. The fraction of its volume below the surface is:

131. A fluid of density 1000 kg/m^3 flows at 5 m/s through a pipe of area 4 10^-4 m^2. The mass flow rate is:

132. Water (rho = 1000 kg/m^3) flows horizontally. At one point P = 2 10^5 Pa and v = 2 m/s; at another v = 6 m/s. The pressure there is:

133. Chimneys draw smoke up better on windy days partly because:

134. A steel ship floats although steel is denser than water because:

135. Water leaks through a small hole 1.8 m below the surface of an open tank. The speed of efflux is (g = 9.8):

136. If a pipe's radius is halved, the fluid speed becomes:

137. A body of volume 0.5 m^3 is fully immersed in a liquid of density 1000 kg/m^3. The upthrust on it is (g = 9.8):

138. A small steel ball dropped into glycerine first accelerates and then:

139. A stream of honey falling from a spoon gets thinner as it falls because:

140. Which is closest to an ideal fluid?

141. Blood is a viscous fluid, so the heart must:

142. Using Stokes' law, the drag on a sphere of radius 0.002 m moving at 0.01 m/s through a fluid of viscosity 1.5 Pa s is:

143. Water (rho = 1000 kg/m^3) flows horizontally. At one point P = 3 10^5 Pa and v = 3 m/s; at another v = 9 m/s. The pressure there is:

144. A body of volume 0.01 m^3 is fully immersed in a liquid of density 800 kg/m^3. The upthrust on it is (g = 9.8):

145. The weight of water displaced by a ship is called its:

146. As the temperature of a gas rises, its viscosity:

147. A non-viscous fluid is one with:

148. Non-viscous flow implies that:

149. Why can't fluid accumulate between two sections of a rigid pipe in steady flow of an incompressible fluid?

150. Because of viscosity, a real fluid flowing through a pipe:

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