Q: Calculate the pressure 150 m below the surface of the sea. The density of sea water is $$1.026\ \mathrm{g/cm}^3. ($$Use $$g = 9.8\ \mathrm{m/s}^2)$$

$$1.51 \times 10^6$\ \mathrm{Pa}$$

Q: Which of the following is the correct conversion for 1 torr to pascals ($$\mathrm{Pa}$$)?

$$1\ \mathrm{torr} = 1.33 \times 10^2$\ \mathrm{Pa}$$

Q: Which equation describes the height $$h of a $$liquid column supported by surface tension $$T in a $$tube of radius $$R$$ and contact angle $$\theta$$?

$$h = \frac{2 T \cos \theta}{R g \rho}$$

Question 1

Which of the following statements best describes Pascal's principle?

Accepted Answer

The increase in pressure at any point in a fluid is transmitted undiminished to all other points in the fluid.

Question 2

A hydraulic lift has a small piston of area $$A_1 = 0.01$$\ \mathrm{m}^2$$ and a large piston of area A_2$ = 0.5\ \mathrm{m}^2. If a $$force $$F_1 = 200$$\ \mathrm{N}$$ is applied to the small piston, what is the force F_2$ exerted by the large piston according to Pascal's principle?

Accepted Answer

$$F_2 = 10$$,000\ \mathrm{N}$$

Question 3

Calculate the pressure 150 m below the surface of the sea. The density of sea water is $$1.026\ \mathrm{g/cm}^3. ($$Use $$g = 9.8\ \mathrm{m/s}^2)$$

Accepted Answer

$$1.51 	imes 10^6$\ \mathrm{Pa}$$

Question 4

Which equation correctly expresses the difference in pressure between two points separated by a vertical distance $$h in a $$fluid of constant density $$\rho$$?

Accepted Answer

$$P_2$$ - $$P_1$$ = \rho g h$$

Question 5

A body is partially submerged in water. According to Archimedes's principle, what is the magnitude of the buoyant force acting on it?

Accepted Answer

Equal to the weight of the displaced fluid.

Question 6

A cuttlefish has a porous bone with density $$0.62\ \mathrm{g/cm}^3$$ and the rest of its body has density $$1.067\ \mathrm{g/cm}^3. If $$the density of sea water is $$1.026\ \mathrm{g/cm}^3$$, what percentage of the body volume $$X$$ must be porous bone for the fish to float?

Accepted Answer

$$X = 9.2\%$$

Question 7

Which of the following best explains why a water strider can walk on water?

Accepted Answer

Surface tension creates a force that supports the insect's weight.

Question 8

If the area of the moving limbs of an animal is $$A$$ and the final velocity of the accelerated water is $$v$$, what is the mass of water accelerated per unit time in the treading motion?

Accepted Answer

$$m = A v \rho_w$$

Question 9

A worm uses its hydrostatic skeleton for movement. If the effective area of the circular muscle per unit length is $$A_M$$ and the force produced per unit area is $$S$$, what is the total force generated along each centimeter of the worm's length?

Accepted Answer

$$f_M = S A_M$$

Question 10

Which of the following is the correct formula for the pressure required to split a cylindrical hydrostatic skeleton, given the force per unit length $$f_M$$ and radius $$r$$?

Accepted Answer

$$P = \frac{f_M}{r}$$

Question 11

Which of the following is the correct conversion for 1 torr to pascals ($$\mathrm{Pa}$$)?

Accepted Answer

$$1\ \mathrm{torr} = 1.33 	imes 10^2$\ \mathrm{Pa}$$

Question 12

An animal of volume $$V$$ and density $$\rho$$ floats with a fraction $$f of $$its volume submerged in water of density $$\rho_w. $$What is the buoyant force acting on the animal?

Accepted Answer

$$F_B = g f V \rho_w$$

Question 13

If the net force on an interior molecule in a liquid is zero, what causes surface tension at the liquid's surface?

Accepted Answer

Molecules at the surface experience a net inward force due to lack of neighboring molecules above.

Question 14

Which formula gives the kinetic energy imparted to the water each second by the limbs of an animal treading water?

Accepted Answer

$$P = \frac{1}{2} m v^2$

Question 15

A column of liquid is supported by surface tension. If the radius of the column is $$R$$, the height is $$h$$, and the density is $$\rho$$, what is the weight $$W of $$the column?

Accepted Answer

$$W = \pi R^2$ h g \rho$$

Question 16

Which equation describes the height $$h of a $$liquid column supported by surface tension $$T in a $$tube of radius $$R$$ and contact angle $$	heta$$?

Accepted Answer

$$h = \frac{2 T \cos 	heta}{R g ho}$$

Question 17

If an animal of volume $$V$$ and density $$\rho$$ floats in water of density $$\rho_w$$, what is the difference between the gravitational and buoyed forces acting on it?

Accepted Answer

$$F_D = g V (\rho - f \rho_w)$$

Question 18

Which of the following is NOT a correct statement about pressure in a fluid at rest?

Accepted Answer

Pressure in a fluid at rest is greater at the surface than at greater depths.

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