Question 1

A block of wood has dimensions $$0.75\,\mathrm{m} 	imes 0.45\,\mathrm{m} 	imes 0.10\,\mathrm{m}$$ and a mass of $$15.0\,\mathrm{kg}. $$What is the density of the wood?

Accepted Answer

$$333\,\mathrm{kg/m^3$}$$

Question 2

Which of the following best describes why ice floats in water?

Accepted Answer

Ice has a lower density than water.

Question 3

A U-tube manometer contains mercury ($$\rho = 13,600\,\mathrm{kg/m^3$}) $$and water ($$\rho = 1,000\,\mathrm{kg/m^3$}). If $$the height difference of mercury is $$0.025\,\mathrm{m}$$, what is the pressure difference between the two sides?

Accepted Answer

$$3330\,\mathrm{Pa}$$

Question 4

A hydraulic lift is used to lift a $$2,000\,\mathrm{kg}$$ car. If the small piston has an area of $$0.015\,\mathrm{m^2$}$$ and the large piston has an area of $$0.45\,\mathrm{m^2$}$$, what force must be applied to the small piston to lift the car?

Accepted Answer

$$1,300\,\mathrm{N}$$

Question 5

A swimmer with a mass of $$72.0\,\mathrm{kg}$$ floats in a pool. If the density of water is $$1,050\,\mathrm{kg/m^3$}$$, what is the minimum volume of water displaced?

Accepted Answer

$$0.0686\,\mathrm{m^3$}$$

Question 6

A chunk of ice ($$\rho_{ice} = 917\,\mathrm{kg/m^3$}) $$floats in fresh water ($$\rho_{water} = 1,000\,\mathrm{kg/m^3$}). $$What percentage of the ice is submerged?

Accepted Answer

$$91.7\%$$

Question 7

A sealed box is submerged $$0.20\,\mathrm{m}$$ below the surface of a fluid. The pressure at the top of the box is $$106.8\,\mathrm{kPa}$$ and the atmospheric pressure is $$100\,\mathrm{kPa}. $$What is the density of the fluid?

Accepted Answer

$$417\,\mathrm{kg/m^3$}$$

Question 8

A soap bubble is released underwater and rises to the surface. As it rises, what happens to its diameter?

Accepted Answer

It increases.

Question 9

Water flows through a pipe with a diameter of $$9.15\,\mathrm{cm} at a $$speed of $$2.23\,\mathrm{m/s}. $$What is the volumetric flow rate?

Accepted Answer

$$0.0147\,\mathrm{m^3$/s}$$

Question 10

A water fountain shoots water to a height of $$0.37\,\mathrm{m}. If $$the exit velocity is $$2.7\,\mathrm{m/s}$$, what is the diameter of the nozzle if the flow rate is $$0.028\,\mathrm{m^3$/s}$$?

Accepted Answer

$$0.082\,\mathrm{m}$$

Question 11

Blood flows through the pulmonary artery with a pressure difference of $$400\,\mathrm{Pa}$$, a radius of $$0.0125\,\mathrm{m}$$, and a length of $$0.06\,\mathrm{m}. If $$the viscosity of blood is $$2.72 	imes 10$$^{-3}$$\,\mathrm{Pa \cdot s}$$, what is the speed of blood flow?

Accepted Answer

$$1.23\,\mathrm{m/s}$$

Question 12

If the atmospheric pressure is $$101,325\,\mathrm{Pa}$$ and the gauge pressure inside a basketball is $$700\,\mathrm{kPa}$$, what is the absolute pressure inside the ball?

Accepted Answer

$$801,325\,\mathrm{Pa}$$

Question 13

A tornado causes the atmospheric pressure outside a house to drop to $$87,000\,\mathrm{Pa}$$ while the pressure inside remains at $$101,325\,\mathrm{Pa}. $$What is the net outward force on a $$50.0\,\mathrm{m^2$}$$ roof?

Accepted Answer

$$717,000\,\mathrm{N}$$

Question 14

Which equation correctly expresses the relationship between pressure, density, gravity, and depth in a fluid?

Accepted Answer

$$P = P_0$ + \rho g h$$

Question 15

A vertical column of fluid has a height $$h$$ and density $$\rho. $$What is the pressure at the bottom of the column due to the fluid alone?

Accepted Answer

$$\rho g h$$

Fluid Mechanics: Density, Pressure, and Applications

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