Question 1

Under standard conditions,the density of air is 1.29 kg/m3.What is the mass of the air inside a room measuring 4.0 m × 3.0 m × 2.0 m?

Accepted Answer

A) 0.32 kg 
B) 3.1 kg 
C) 31 kg 
D) 1.9 kg 
E) 19 kg

Question 2

Motor oil,with a viscosity of 0.25 N ∙ s/m2,is flowing through a tube that has a radius of 5.0 mm and is 25 cm long.The drop in pressure is 300 kPa.What is the volume of oil flowing through the tube per second?

Accepted Answer

A) 0.00038 m3/s 
B) 0.025 m3/s 
C) 0.0012 m3/s 
D) 4.7 m3/s 
E) 7.5 m3/s

Question 3

Salt water is denser than fresh water.A ship floats in both fresh water and salt water.Compared to the fresh water,the volume of water displaced in the salt water is

Accepted Answer

A) more. 
B) less. 
C) the same. 
D) Cannot be determined because we do not know the volume of the ship.

Question 4

Water flowing through a cylindrical pipe suddenly comes to a section of pipe where the diameter decreases to 86% of its previous value.If the speed of the water in the larger section of the pipe was 
What is its speed in this smaller section if the water behaves like an ideal incompressible fluid?

Accepted Answer

A) 43 m/s 
B) 37 m/s 
C) 28 m/s 
D) 24 m/s

Question 5

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 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 initial force that must be applied to the smaller piston in order to start lifting the car? For purposes of this problem,neglect the weight of the pistons.

Accepted Answer

A) 727 N 
B) 926 N 
C) 2.90 kN 
D) 3.33 kN 
E) 1.20 kN

Question 6

A block of metal weighs 40 N in air and 30 N in water.What is the buoyant force on the block due to the water? The density of water is 1000 kg/m3.

Accepted Answer

A) 10 N 
B) 30 N 
C) 40 N 
D) 70 N

Question 7

Calculate the pressure exerted on the ground due to the weight of 
Person standing on one foot.if the bottom of the person's foot is 
Wide and 
Long.

Accepted Answer

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

Question 8

The deepest point of the Pacific Ocean is 11,033 m,in the Mariana Trench.What is the gauge pressure in the water at that point? The density of seawater is 1025 kg/m3.

Accepted Answer

A) 5.55 × 107 Pa 
B) 8.88 × 107 Pa 
C) 1.11 × 108 Pa 
D) 2.22 × 108 Pa 
E) 3.33 × 108 Pa

Question 9

Two horizontal pipes have the same diameter,but pipe B is twice as long as pipe A.Water undergoes viscous flow in both pipes,subject to the same pressure difference across the lengths of the pipes.If the flow rate in pipe B is Q = 
What is the flow rate in pipe A?

Accepted Answer

A) 2Q 
B) 4Q 
C) 8Q 
D) 16Q 
E) Q

Question 10

A boat loaded with rocks is floating in a swimming pool.If the rocks are thrown into the pool,the water level in the pool,after the rocks have settled to the bottom,

Accepted Answer

A) rises. 
B) falls. 
C) stays the same.

Question 11

A hollow sphere of negligible mass and radius R is completely filled with a liquid so that its density is ρ.You now enlarge the sphere so its radius is 2R and completely fill it with the same liquid.What is the density of the enlarged sphere?

Accepted Answer

A) 8 ρ 
B) 4 ρ 
C) ρ/2 
D) ρ 
E) ρ/8

Question 12

When a box rests on a round sheet of wood on the ground,it exerts an average pressure p on the wood.If the wood is replaced by a sheet that has half the diameter of the original piece,what is the new average pressure?

Accepted Answer

A) 4p 
B) 2p 
C) p  
D) p/2 
E) p/4

Question 13

A brick weighs 50.0 N,and measures 30.0 cm × 10.0 cm × 4.00 cm.What is the maximum pressure it can exert on a horizontal surface due to its weight?

Accepted Answer

A) 1.25 Pa 
B) 12.5 Pa 
C) 1.25 kPa 
D) 12.5 kPa

Question 14

A water tank is filled to a depth of 10 m,and the bottom of the tank is 20 m above ground.A water-filled hose that is 2.0 cm in diameter extends from the bottom of the tank to the ground,but no water is flowing in this hose.The water pressure at ground level in the hose is closest to which of the following values? The density of water is 1000 kg/m3.

Accepted Answer

A) 3.9 × 105 N/m2 
B) 2.0 × 104 N/m2 
C) 9.2 N/m2 
D) The question cannot be answered because the cross sectional area of the tank is needed.

Question 15

Water flows through a horizontal pipe of cross-sectional area 10.0 cm2 at a pressure of 0.250 atm with a flow rate is 1.00 L/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? The density of water is 1000 kg/m3,and treat it as an ideal incompressible fluid.

Accepted Answer

A) 0.110 atm 
B) 0.235 atm 
C) 0.200 atm 
D) 0.157 atm 
E) 7700 Pa

Question 16

A compressed gas with a total mass of 
Is stored in a spherical container having a radius of 0.521 m.What is the density of the compressed gas?

Accepted Answer

A) 181 kg/m3 
B) 110 kg/m3 
C) 134 kg/m3 
D) 161 kg/m3

Question 17

Fluid flows at 2.0 m/s through a pipe of diameter 3.0 cm.What is the volume flow rate of the fluid?

Accepted Answer

A) 1.4 × 10-3 m3/s 
B) 5.7 × 10-3 m3/s 
C) 14 m3/s 
D) 57 m3/s

Question 18

A hot air balloon along with its cargo has a mass of 4.0 × 105 kg,and it holds 7.0 × 105 m3 of hot air.It is floating at a constant height in air with a density of 1.29 kg/m3.What is the density of the hot air in the balloon?

Accepted Answer

A) 1.4 kg/m3 
B) 0.72 kg/m3 
C) 0.57 kg/m3 
D) 0.86 kg/m3 
E) 0.43 kg/m3

Question 19

An object weighs 7.84 N when it is in air and 6.86 N when it is immersed in water of density 1000 kg/m3.What is the density of the object?

Accepted Answer

A) 6000 kg/m3 
B) 7000 kg/m3 
C) 8000 kg/m3 
D) 9000 kg/m3

Question 20

Two horizontal pipes are the same length,but pipe B has twice the diameter of pipe A.Water undergoes viscous flow in both pipes,subject to the same pressure difference across the lengths of the pipes.If the flow rate in pipe A is Q = 
,what is the flow rate in pipe B?

Accepted Answer

A) 2Q 
B) 4Q 
C) 8Q 
D) 16Q 
E) Q

Exam 15: Fluids

Under standard conditions,the density of air is 1.29 kg/m³.What is the mass of the air inside a room measuring 4.0 m × 3.0 m × 2.0 m?

Motor oil,with a viscosity of 0.25 N ∙ s/m²,is flowing through a tube that has a radius of 5.0 mm and is 25 cm long.The drop in pressure is 300 kPa.What is the volume of oil flowing through the tube per second?

Salt water is denser than fresh water.A ship floats in both fresh water and salt water.Compared to the fresh water,the volume of water displaced in the salt water is

Water flowing through a cylindrical pipe suddenly comes to a section of pipe where the diameter decreases to 86% of its previous value.If the speed of the water in the larger section of the pipe was What is its speed in this smaller section if the water behaves like an ideal incompressible fluid?

A block of metal weighs 40 N in air and 30 N in water.What is the buoyant force on the block due to the water? The density of water is 1000 kg/m³.

Calculate the pressure exerted on the ground due to the weight of Person standing on one foot.if the bottom of the person's foot is Wide and Long.

The deepest point of the Pacific Ocean is 11,033 m,in the Mariana Trench.What is the gauge pressure in the water at that point? The density of seawater is 1025 kg/m³.

Two horizontal pipes have the same diameter,but pipe B is twice as long as pipe A.Water undergoes viscous flow in both pipes,subject to the same pressure difference across the lengths of the pipes.If the flow rate in pipe B is Q = What is the flow rate in pipe A?

A boat loaded with rocks is floating in a swimming pool.If the rocks are thrown into the pool,the water level in the pool,after the rocks have settled to the bottom,

A hollow sphere of negligible mass and radius R is completely filled with a liquid so that its density is ρ.You now enlarge the sphere so its radius is 2R and completely fill it with the same liquid.What is the density of the enlarged sphere?

When a box rests on a round sheet of wood on the ground,it exerts an average pressure p on the wood.If the wood is replaced by a sheet that has half the diameter of the original piece,what is the new average pressure?

A brick weighs 50.0 N,and measures 30.0 cm × 10.0 cm × 4.00 cm.What is the maximum pressure it can exert on a horizontal surface due to its weight?

A compressed gas with a total mass of Is stored in a spherical container having a radius of 0.521 m.What is the density of the compressed gas?

Fluid flows at 2.0 m/s through a pipe of diameter 3.0 cm.What is the volume flow rate of the fluid?

A hot air balloon along with its cargo has a mass of 4.0 × 10⁵ kg,and it holds 7.0 × 10⁵ m³ of hot air.It is floating at a constant height in air with a density of 1.29 kg/m³.What is the density of the hot air in the balloon?

An object weighs 7.84 N when it is in air and 6.86 N when it is immersed in water of density 1000 kg/m³.What is the density of the object?

Two horizontal pipes are the same length,but pipe B has twice the diameter of pipe A.Water undergoes viscous flow in both pipes,subject to the same pressure difference across the lengths of the pipes.If the flow rate in pipe A is Q = ,what is the flow rate in pipe B?