Question 1

An object has a volume of 4.0 m3 and weighs 40,000 N. What will its apparent weight be in water of density 1000 kg/m3?

Accepted Answer

A)  40,000 N 
B)  39,200 N 
C)  9,800 N 
D)  800 N 
A)  40,000 N 
B)  39,200 N 
C)  9,800 N 
D)  800 N D

Question 2

How many grams of ethanol (density 0.80 g/cm3) should be added to 5.0 g of chloroform (density 1.5 g/cm3) if the resulting mixture is to have a density of 1.2 g/cm3? Assume that the fluids do not change their volumes when they are mixed.

Accepted Answer

A)  2.0 g 
B)  2.4 g 
C)  1.8 g 
D)  4.4 g 
E)  1.6 g 
A)  2.0 g 
B)  2.4 g 
C)  1.8 g 
D)  4.4 g 
E)  1.6 g A

Question 3

Ideal incompressible water flows through a horizontal pipe of cross-sectional area 10.0 cm2 at a pressure of 0.250 atm with a volume flow rate of 1.00 × 10-3 m3/s. At a valve, the effective cross-sectional area of the pipe is reduced to 5.00 cm2. What is the pressure at the valve?

Accepted Answer

A)  0.112 atm 
B)  0.157 atm 
C)  0.200 atm 
D)  0.235 atm 
A)  0.112 atm 
B)  0.157 atm 
C)  0.200 atm 
D)  0.235 atm D

Question 4

A 100-kg person sits on a 5-kg bicycle. The total weight is borne equally by the two wheels of the bicycle. The tires are 2.0 cm wide and are inflated to a gauge pressure of 8.0 × 105 Pa. What length of each tire is in contact with the ground?

Accepted Answer

A)  1.6 cm 
B)  1.8 cm 
C)  3.2 cm 
D)  2.4 cm 
E)  6.4 cm 
A)  1.6 cm 
B)  1.8 cm 
C)  3.2 cm 
D)  2.4 cm 
E)  6.4 cm

Question 5

A 10-kg piece of aluminum sits at the bottom of a lake, right next to a 10-kg piece of lead, which is much denser than aluminum. Which one has the greater buoyant force on it?

Accepted Answer

A)  the aluminum 
B)  the lead 
C)  Both have the same buoyant force. 
D)  It cannot be determined without knowing their volumes. 
A)  the aluminum 
B)  the lead 
C)  Both have the same buoyant force. 
D)  It cannot be determined without knowing their volumes.

Question 6

A circular window 30 cm in diameter in a submarine can withstand a net maximum force of 5.20 × 105 N without damage. What is the maximum depth in a fresh-water lake to which the submarine can go without damaging the window? The density of fresh water is 1000 kg/m3.

Accepted Answer

A)  680 m 
B)  740 m 
C)  1200 m 
D)  750 m 
A)  680 m 
B)  740 m 
C)  1200 m 
D)  750 m

Question 7

Glycerin, with a viscosity of 1.5 N ∙ s/m2, is flowing with an average speed of 1.2 m/s through a tube that has a radius of 5.0 mm and is 25 cm long. What is the drop in pressure over the length of this pipe?

Accepted Answer

A)  140 kPa 
B)  46 kPa 
C)  72 kPa 
D)  76 kPa 
E)  130 kPa 
A)  140 kPa 
B)  46 kPa 
C)  72 kPa 
D)  76 kPa 
E)  130 kPa

Question 8

A 1938 nickel has a diameter of 21.21 mm, a thickness of 1.95 mm, and weighs 0.04905 N. What is its density?

Accepted Answer

A)  1.37 × 10-4 kg/m3 
B)  1.82 × 103 kg/m3 
C)  19.3 × 103 kg/m3 
D)  3.63 × 103 kg/m3 
E)  7.26 × 103 kg/m3 
A)  1.37 × 10-4 kg/m3 
B)  1.82 × 103 kg/m3 
C)  19.3 × 103 kg/m3 
D)  3.63 × 103 kg/m3 
E)  7.26 × 103 kg/m3

Question 9

A round coin has a diameter of 19.55 mm, a thickness of 1.55 mm, and a mass of 2.50 g. What is its density?

Accepted Answer

A)  5.37 × 103 kg/m3 
B)  21.5 × 103 kg/m3 
C)  1.34 × 103 kg/m3 
D)  2.68 × 103 kg/m3 
E)  1.86 × 10-4 kg/m3 
A)  5.37 × 103 kg/m3 
B)  21.5 × 103 kg/m3 
C)  1.34 × 103 kg/m3 
D)  2.68 × 103 kg/m3 
E)  1.86 × 10-4 kg/m3

Question 10

If a ship has a mass of 10 million kilograms, what volume of fresh water must it displace in order to float? The density of water is 1000 kg/m3.

Accepted Answer

A)  1010 m3 
B)  1012 m3 
C)  104 m3 
D)  107 m3 
E)  108 m3 
A)  1010 m3 
B)  1012 m3 
C)  104 m3 
D)  107 m3 
E)  108 m3

Question 11

When a heavy metal block is supported by a cylindrical vertical post of radius R, it exerts a force F on the post. If the diameter of the post is increased to 2R, what force does the block now exert on the post?

Accepted Answer

A)  F/4 
B)  F/2 
C)  F/ $\sqrt { 2 }$ 
D)  F 
E)  2F 
A)  F/4 
B)  F/2 
C)  F/ $\sqrt { 2 }$ 
D)  F 
E)  2F

Question 12

A polar bear of mass 200 kg stands on an ice floe that is a uniform 1.0 m thick. What is the minimum area of the floe that will just support the bear in saltwater of density 1030 kg/m3? The density of ice is 980 kg/m3.

Accepted Answer

A)  1.0 m2 
B)  2.0 m2 
C)  3.0 m2 
D)  4.0 m2 
A)  1.0 m2 
B)  2.0 m2 
C)  3.0 m2 
D)  4.0 m2

Question 13

A 12,000-N car is raised using a hydraulic lift, which consists of a U-tube with arms of unequal areas, filled with oil with a density of 800 kg/m3 and capped at both ends with tight-fitting pistons. The wider arm of the U-tube has a radius of 18.0 cm and the narrower arm has a radius of 5.00 cm. The car rests on the piston on the wider arm of the U-tube. The pistons are initially at the same level. What is the force that must be applied to the smaller piston in order to lift the car after it has been raised 1.20 m? For purposes of this problem, neglect the weight of the pistons.

Accepted Answer

A)  0.954 kN 
B)  1.88 kN 
C)  1.96 kN 
D)  3.67 kN 
E)  1.20 kN 
A)  0.954 kN 
B)  1.88 kN 
C)  1.96 kN 
D)  3.67 kN 
E)  1.20 kN

Question 14

An air bubble underwater has the same pressure as that of the surrounding water. As the air bubble rises toward the surface (and its temperature remains constant), the volume of the air bubble

Accepted Answer

A)  increases. 
B)  decreases. 
C)  remains constant. 
D)  increases or decreases, depending on the rate it rises. 
A)  increases. 
B)  decreases. 
C)  remains constant. 
D)  increases or decreases, depending on the rate it rises.

Question 15

Calculate the pressure exerted on the ground due to the weight of $\text { a } 79 - \mathrm { kg }$ person standing on one foot. if the bottom of the person's foot is $13 \mathrm {~cm}$ wide and $28 \mathrm {~cm}$ long.

Accepted Answer

A)  2.1 × 104 Pa 
B)  2.2 × 103 Pa 
C)  4.8 × 104 Pa 
D)  5.3 × 104 Pa 
A)  2.1 × 104 Pa 
B)  2.2 × 103 Pa 
C)  4.8 × 104 Pa 
D)  5.3 × 104 Pa

Question 16

A spherical ball of lead (density 11.3 g/cm3) is placed in a tub of mercury (density 13.6 g/cm3). Which answer best describes the result?

Accepted Answer

A)  The lead ball will float with about 83% of its volume above the surface of the mercury. 
B)  The lead ball will float with its top exactly even with the surface of the mercury. 
C)  The lead ball will float with about 17% of its volume above the surface of the mercury. 
D)  The lead will sink to the bottom of the mercury. 
A)  The lead ball will float with about 83% of its volume above the surface of the mercury. 
B)  The lead ball will float with its top exactly even with the surface of the mercury. 
C)  The lead ball will float with about 17% of its volume above the surface of the mercury. 
D)  The lead will sink to the bottom of the mercury.

Question 17

A piece of iron rests on top of a piece of wood floating in a bathtub. If the iron is removed from the wood, and kept out of the water, what happens to the water level in the tub?

Accepted Answer

A)  It goes up. 
B)  It goes down. 
C)  It does not change. 
D)  It is impossible to determine from the information given. 
A)  It goes up. 
B)  It goes down. 
C)  It does not change. 
D)  It is impossible to determine from the information given.

Question 18

A 50-cm3 block of wood is floating on water, and a 50-cm3 chunk of iron is totally submerged in the water. Which one has the greater buoyant force on it?

Accepted Answer

A)  the wood 
B)  the iron 
C)  Both have the same buoyant force. 
D)  It cannot be determined without knowing their densities. 
A)  the wood 
B)  the iron 
C)  Both have the same buoyant force. 
D)  It cannot be determined without knowing their densities.

Question 19

A wooden raft has a mass of 55 kg. When empty it floats in water (density $\left. 1000 \mathrm {~kg} / \mathrm { m } ^ { 3 } \right)$ with 64% of its volume submerged. What maximum mass of sand can be put on the raft without sinking it?

Accepted Answer

The answer of A wooden raft has a mass of...

Question 20

A 4.7-kg solid sphere, made of metal whose density is 4000 kg/ $m ^ { 3 }$ , hangs by a light cord. When the sphere is immersed in water, what is the tension in the cord? The density of water is 1000 kg/m3.

Accepted Answer

A)  35 N 
B)  40 N 
C)  46 N 
D)  52 N 
E)  58 N 
A)  35 N 
B)  40 N 
C)  46 N 
D)  52 N 
E)  58 N

Exam 13: Fluids

An object has a volume of 4.0 m3 and weighs 40,000 N. What will its apparent weight be in water of density 1000 kg/m3?

How many grams of ethanol (density 0.80 g/cm3) should be added to 5.0 g of chloroform (density 1.5 g/cm3) if the resulting mixture is to have a density of 1.2 g/cm3? Assume that the fluids do not change their volumes when they are mixed.

Ideal incompressible water flows through a horizontal pipe of cross-sectional area 10.0 cm2 at a pressure of 0.250 atm with a volume flow rate of 1.00 × 10-3 m3/s. At a valve, the effective cross-sectional area of the pipe is reduced to 5.00 cm2. What is the pressure at the valve?

A 100-kg person sits on a 5-kg bicycle. The total weight is borne equally by the two wheels of the bicycle. The tires are 2.0 cm wide and are inflated to a gauge pressure of 8.0 × 105 Pa. What length of each tire is in contact with the ground?

A 10-kg piece of aluminum sits at the bottom of a lake, right next to a 10-kg piece of lead, which is much denser than aluminum. Which one has the greater buoyant force on it?

A circular window 30 cm in diameter in a submarine can withstand a net maximum force of 5.20 × 105 N without damage. What is the maximum depth in a fresh-water lake to which the submarine can go without damaging the window? The density of fresh water is 1000 kg/m3.

Glycerin, with a viscosity of 1.5 N ∙ s/m2, is flowing with an average speed of 1.2 m/s through a tube that has a radius of 5.0 mm and is 25 cm long. What is the drop in pressure over the length of this pipe?

A 1938 nickel has a diameter of 21.21 mm, a thickness of 1.95 mm, and weighs 0.04905 N. What is its density?

A round coin has a diameter of 19.55 mm, a thickness of 1.55 mm, and a mass of 2.50 g. What is its density?

If a ship has a mass of 10 million kilograms, what volume of fresh water must it displace in order to float? The density of water is 1000 kg/m3.

When a heavy metal block is supported by a cylindrical vertical post of radius R, it exerts a force F on the post. If the diameter of the post is increased to 2R, what force does the block now exert on the post?

A polar bear of mass 200 kg stands on an ice floe that is a uniform 1.0 m thick. What is the minimum area of the floe that will just support the bear in saltwater of density 1030 kg/m3? The density of ice is 980 kg/m3.

An air bubble underwater has the same pressure as that of the surrounding water. As the air bubble rises toward the surface (and its temperature remains constant), the volume of the air bubble

Calculate the pressure exerted on the ground due to the weight of a 79−kg\text { a } 79 - \mathrm { kg } a 79−kg person standing on one foot. if the bottom of the person's foot is 13 cm13 \mathrm {~cm}13 cm wide and 28 cm28 \mathrm {~cm}28 cm long.

A spherical ball of lead (density 11.3 g/cm3) is placed in a tub of mercury (density 13.6 g/cm3). Which answer best describes the result?

A piece of iron rests on top of a piece of wood floating in a bathtub. If the iron is removed from the wood, and kept out of the water, what happens to the water level in the tub?

A 50-cm3 block of wood is floating on water, and a 50-cm3 chunk of iron is totally submerged in the water. Which one has the greater buoyant force on it?

A wooden raft has a mass of 55 kg. When empty it floats in water (density 1000 kg/m3)\left. 1000 \mathrm {~kg} / \mathrm { m } ^ { 3 } \right)1000 kg/m3) with 64% of its volume submerged. What maximum mass of sand can be put on the raft without sinking it?

A 4.7-kg solid sphere, made of metal whose density is 4000 kg/ m3m ^ { 3 }m3 , hangs by a light cord. When the sphere is immersed in water, what is the tension in the cord? The density of water is 1000 kg/m3.

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Filters

An object has a volume of 4.0 m³ and weighs 40,000 N. What will its apparent weight be in water of density 1000 kg/m³?

How many grams of ethanol (density 0.80 g/cm³) should be added to 5.0 g of chloroform (density 1.5 g/cm³) if the resulting mixture is to have a density of 1.2 g/cm³? Assume that the fluids do not change their volumes when they are mixed.

Ideal incompressible water flows through a horizontal pipe of cross-sectional area 10.0 cm² at a pressure of 0.250 atm with a volume flow rate of 1.00 × 10^-3 m³/s. At a valve, the effective cross-sectional area of the pipe is reduced to 5.00 cm². What is the pressure at the valve?

A 100-kg person sits on a 5-kg bicycle. The total weight is borne equally by the two wheels of the bicycle. The tires are 2.0 cm wide and are inflated to a gauge pressure of 8.0 × 10⁵ Pa. What length of each tire is in contact with the ground?

A circular window 30 cm in diameter in a submarine can withstand a net maximum force of 5.20 × 10⁵ N without damage. What is the maximum depth in a fresh-water lake to which the submarine can go without damaging the window? The density of fresh water is 1000 kg/m³.

Glycerin, with a viscosity of 1.5 N ∙ s/m², is flowing with an average speed of 1.2 m/s through a tube that has a radius of 5.0 mm and is 25 cm long. What is the drop in pressure over the length of this pipe?

If a ship has a mass of 10 million kilograms, what volume of fresh water must it displace in order to float? The density of water is 1000 kg/m³.

A polar bear of mass 200 kg stands on an ice floe that is a uniform 1.0 m thick. What is the minimum area of the floe that will just support the bear in saltwater of density 1030 kg/m³? The density of ice is 980 kg/m³.

Calculate the pressure exerted on the ground due to the weight of $\text { a } 79 - \mathrm { kg }$ person standing on one foot. if the bottom of the person's foot is $13 \mathrm {~cm}$ wide and $28 \mathrm {~cm}$ long.

A spherical ball of lead (density 11.3 g/cm³) is placed in a tub of mercury (density 13.6 g/cm³). Which answer best describes the result?

A 50-cm³ block of wood is floating on water, and a 50-cm³ chunk of iron is totally submerged in the water. Which one has the greater buoyant force on it?

A wooden raft has a mass of 55 kg. When empty it floats in water (density $\left. 1000 \mathrm {~kg} / \mathrm { m } ^ { 3 } \right)$ with 64% of its volume submerged. What maximum mass of sand can be put on the raft without sinking it?

A 4.7-kg solid sphere, made of metal whose density is 4000 kg/ $m ^ { 3 }$ , hangs by a light cord. When the sphere is immersed in water, what is the tension in the cord? The density of water is 1000 kg/m³.