Q: A steel wrench has a mass of 0.5 kg and a volume of 6.4 \times $$10^{-5}$$ \text{ m}^3. What is its density?

$$\rho = \frac{0.5}{6.4 \times 10$$^{-5}$$} = 7.81 \times 10$$^{3}$$ \text{ kg/m}^3$$

Q: A diver is 20 m below the surface of freshwater ($$\rho = 1.0 \times 10$$^{3}$$ \text{ kg/m}^3). $$What is the gauge pressure at this depth? ($$g = 9.8 \text{ m/s}^2)$$

$$p = \rho g h = 1.0 \times 10$$^{3}$$ \times 9.8 \times 20 = 1.96 \times 10$$^{5}$$ \text{ Pa}$$

Q: According to Pascal's law, if a force of 100 N is applied to a piston of area $$0.01 \text{ m}^2$$, what is the pressure transmitted to the fluid?

$$p = \frac{F}{A} = \frac{100}{0.01} = 1.0 \times 10$$^{4}$$ \text{ Pa}$$

Q: A car tire has a gauge pressure of $$2.2 \times 10$$^{5}$$ \text{ Pa}. If $$atmospheric pressure is $$1.0 \times 10$$^{5}$$ \text{ Pa}$$, what is the absolute pressure inside the tire?

$$p_{abs} = p_{atm} + p_{gauge} = 1.0 \times 10$$^{5}$$ + 2.2 \times 10$$^{5}$$ = 3.2 \times 10$$^{5}$$ \text{ Pa}$$

Question 1

A steel wrench has a mass of 0.5 kg and a volume of 6.4 	imes $$10^{-5}$$ 	ext{ m}^3. What is its density?

Accepted Answer

$$ho = \frac{0.5}{6.4 	imes 10$$^{-5}$$} = 7.81 	imes 10$$^{3}$$ 	ext{ kg/m}^3$$

Question 2

Which of the following statements about pressure in a fluid at rest is correct?

Accepted Answer

Pressure acts perpendicular to any surface in contact with the fluid.

Question 3

A diver is 20 m below the surface of freshwater ($$ho = 1.0 	imes 10$$^{3}$$ 	ext{ kg/m}^3). $$What is the gauge pressure at this depth? ($$g = 9.8 	ext{ m/s}^2)$$

Accepted Answer

$$p = ho g h = 1.0 	imes 10$$^{3}$$ 	imes 9.8 	imes 20 = 1.96 	imes 10$$^{5}$$ 	ext{ Pa}$$

Question 4

According to Pascal's law, if a force of 100 N is applied to a piston of area $$0.01 	ext{ m}^2$$, what is the pressure transmitted to the fluid?

Accepted Answer

$$p = \frac{F}{A} = \frac{100}{0.01} = 1.0 	imes 10$$^{4}$$ 	ext{ Pa}$$

Question 5

A car tire has a gauge pressure of $$2.2 	imes 10$$^{5}$$ 	ext{ Pa}. If $$atmospheric pressure is $$1.0 	imes 10$$^{5}$$ 	ext{ Pa}$$, what is the absolute pressure inside the tire?

Accepted Answer

$$p_{abs} = p_{atm} + p_{gauge} = 1.0 	imes 10$$^{5}$$ + 2.2 	imes 10$$^{5}$$ = 3.2 	imes 10$$^{5}$$ 	ext{ Pa}$$

Question 6

A block of wood floats in water. According to Archimedes's principle, what is the magnitude of the buoyant force acting on the block?

Accepted Answer

Equal to the weight of the water displaced by the block.

Question 7

A water strider can walk on water due to which property of fluids?

Accepted Answer

Surface tension

Question 8

Which of the following best describes laminar flow in a fluid?

Accepted Answer

Adjacent layers of fluid slide smoothly past each other and the flow is steady.

Question 9

A pipe narrows from a cross-sectional area of $$0.05 	ext{ m}^2 to$$ $$0.01 	ext{ m}^2. If $$the fluid speed in the wider section is $$2 	ext{ m/s}$$, what is the speed in the narrow section? (Assume incompressible flow.)

Accepted Answer

$$A_1$$ $$v_1$$ = $$A_2$$ $$v_2$$ \Rightarrow $$v_2$$ = \frac{$$A_1$$ $$v_1$$}{$$A_2$$} = \frac{0.05 	imes 2}{0.01} = 10 	ext{ m/s}$$

Question 10

Bernoulli's equation relates which three quantities at different points in a flowing fluid?

Accepted Answer

Pressure, kinetic energy per unit volume, and potential energy per unit volume

Question 11

Blood pressure readings are typically given in mm Hg. If a healthy giraffe needs a systolic blood pressure of 280 mm Hg to supply blood to its brain, what physical principle explains this requirement?

Accepted Answer

Bernoulli's equation, which shows pressure decreases as blood rises to a greater height.

Question 12

A Venturi meter measures fluid flow by comparing pressures at two points. If the fluid speed increases at the throat, what happens to the pressure there?

Accepted Answer

The pressure decreases at the throat.

Question 13

Which of the following is true about viscosity in fluids?

Accepted Answer

Viscosity is a measure of internal friction, causing slower flow near pipe walls.

Question 14

Lava flows more easily when it is hotter. What does this indicate about the relationship between temperature and viscosity?

Accepted Answer

Viscosity decreases as temperature increases.

Question 15

A patient’s blood pressure is measured at the ankle and found to be higher than at the upper arm. What explains this difference?

Accepted Answer

Pressure increases with depth in a fluid due to $$p = p_0$ + \rho g h.$$

Question 16

Which of the following best describes turbulent flow?

Accepted Answer

The flow pattern changes continuously and is not steady.

Question 17

An airplane wing generates lift because:

Accepted Answer

Air moves faster over the top, lowering pressure above the wing according to Bernoulli's principle.

Question 18

A cylindrical pipe carries water with a parabolic velocity profile. Where is the flow speed greatest?

Accepted Answer

At the center of the pipe.

Question 19

A doctor listens to a patient’s blood flow with a stethoscope and hears a noise. What does this indicate about the flow in the aorta?

Accepted Answer

The flow has become turbulent due to a disturbance.

Fluid Mechanics: Key Concepts and Applications

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