CH 7- 10

Suppose that the viscosity of blood is increased by a factor of 2. By what factor does the flow rate change? 1 2 1/2 1/4 1/16

1/2

-40 C to F

-40 F

Liquid flows through a pipe of diameter 3.0 cm at 2.0 m/s. Find the flow rate.

1.4 x 10^-3 m^3/s

What is the pressure generated by sea water at a depth of 15.0 m? (The density of seawater is 1.03× 103 kg/m3.)

1.51 x 10^5

A child pulls on a wagon with a force of 75 N. If the wagon moves a total of 42 m in 3.1 min, what is the average power delivered by the child?

17 W

An object is lifted vertically 2.0 m. If the object weighs 90 N, how much work was done by the lifting force?

180 J

A window glass 0.50-cm thick has dimensions of 3.0 m by 1.5 m. If the outside temperature is -10°C and the inside temperature 20°C, what is the rate of heat conduction through the window? Assume the thermal conductivity of window glass is 0.75 J/(s.m.K).

20 kW

An object has a volume of 4x106 cm3 is totally submerged in water. What are the volume of water displaced by the object and the buoyant force on the object? (density of water=1000 kg/m3)

4 m^3 39200 N

What are the correct units of pressure? (There may be more than one correct answer.)

N/m^2 Pa

Water flows through a pipe. The diameter of the pipe at point B is larger than at point A. Where is the speed of the water greater? point A point B same at both A and B cannot be determined from the information given

point A

Which force below does the most work? All three displacements are the same.

the 6N force

Which has the greatest effect on the flow of fluid through a narrow pipe? the fluid viscosity the pressure difference the length of the pipe the radius of the pipe

the radius of the pipe

A roller coaster of mass m starts from rest at its highest point and then descends on its frictionless track. Its speed is v when it reaches ground level. What was its kinetic energy when its height was three-quarters of its starting point?

1/8 𝑚𝑣^2(=1/4(1/2𝑚𝑣^2))

A block of metal weighs 40 N in air and 30 N in water. What is the buoyant force of the water?

10 N

10 N of force is applied to an area of 1 cm2. What is the pressure on this area?

100,000 N/m^2

A plastic block of dimensions 2.00 cm × 3.00 cm × 4.00 cm has a mass of 30.0 g. What is its density in kg/m3?

1250 kg/m^3

Mercury has a density of 13.6 g/cm3. What is its density in kg/m3?

13600 kg/m^3

Suppose that the radius of a tube is increased by a factor of 2. By what factor does the flow rate change? 2 1/2 4 8 16

16

In a blood vessel, suppose the initial blood flow rate is 100 cm3/s. Calculate the new flow rate if double the radius of the blood vessel without changing anything else.

1600 cm^3/s

Suppose that the pressure difference between the two ends of a tube is increased by a factor of 2. By what factor does the flow rate change? 1 2 1/2 1/4

2

What is the gauge pressure if the absolute pressure is 3 atm?

2 atm

68 F to C

20 C

A horizontal force of 200 N is applied to move a 55-kg cart, initially at rest, across a 10 m level surface. What is the final kinetic energy of the cart? (Hint: Use Work-Energy Theorem.)

2000 J

The temperature changes from 35°F during the night to 75°F during the day. How many degree Celsius change is this?

22 C

A brick is moving at a speed of 3 m/s and a pebble is moving at a speed of 5 m/s. If both objects have the same kinetic energy, what is the ratio of the brick's mass to the rock's mass?

25 to 9

A person lifts a 20 kg box from the ground to a height of 1.0 m. A metabolic measurement shows that in doing this work her body uses 780 J of energy. What is her efficiency?

25%

An ideal fluid flows at 12 m/s in a horizontal pipe. If the pipe widens to twice its original radius, what is the flow speed in the wider section?

3.0 m/s

Matthew pulls his little sister Sarah in a sled on an icy surface (assume no friction), with a force of 60.0 N at an angle of 37.0° upward from the horizontal. If he pulls her a distance of 12.0 m, what is the work done by Matthew?

575 J

An ideal fluid flows at 12 m/s in a horizontal pipe. If the pipe widens to twice its area, what is the flow speed in the wider section?

6 m/s

A 15.0-kg object is moved from a height of 7.00 m above a floor to a height of 13.0 m above the floor. What is the change in gravitational potential energy?

882 J

Aluminum rod 1 is 10 cm long, while aluminum rod 2 is 20 cm long. Both rods are heated and increase the temperature by 20°C. After heating, which rod has undergone the greatest change in length? Rod 1 Rod 2 Both the same Not enough information

Rod 2

A roller coaster starts from rest at its highest point, h, and then descends on its frictionless track. What was its kinetic energy when its height was three quarters of its starting point? a. 1/4 mgh b. 1/2 mgh c. 3/4 mgh d. mgh

a. 1/4 mgh

If you double the thickness of a wall built from a homogeneous material, the rate of heat loss for a given temperature difference across the thickness will a. become one-half of its original value b. also double c. become one-fourth of its original value d. none of the above

a. become one-half of its original value

Of the following, which is not a unit of power? a. watt/second b. newton-meter/second c. joule/second d. watt

a. watt/second

Consider two neighboring rectangular houses built from the same materials. One of the houses has twice the length, width, and height of the other. Under identical climatic conditions, compared to the small house, the larger house would need heat supplied at a. twice the rate b. 4 times the rate c. 8 times the rate d. 16 times the rate

b. 4 times the rate

Oxygen molecules are 16 times more massive than hydrogen molecules. At a given temperature, H2 and O2 have the same kinetic energy. How do their average molecular speeds compare? The oxygen molecules are moving a. four times faster than the hydrogen molecules b. at 1/4 the speed of the hydrogen molecules c. sixteen times faster than the hydrogen molecules d. at 1/16 the speed of the hydrogen molecules

b. at 1/4 the speed of the hydrogen molecules

As shown in the figure, a bimetallic strip, consisting of metal G on the top and metal H on the bottom, is rigidly attached to a wall at the left. The coefficient of linear thermal expansion for metal G is greater than that of metal H. If the strip is uniformly heated, it will a. curve upward b. curve downward c. remain horizontal, but get longer d. remain horizontal, but get shorter

b. curve downward

100 J is added to a sample of gas as heat. The gas then expands against a piston, doing 70 J of work. During this process the thermal energy of the gas a. increases by 70 J b. increases by 30 J c. decreases by 70 J d. decreases by 30 J

b. increases by 30 J

You throw a ball straight up. The sign of the work done by gravity while the ball goes up is a. positive b. negative c. positive at the beginning and negative at the end d. could be positive or negative depending on the weight

b. negative

Two objects, one of mass m and the other of mass 2m, are dropped from the top of a building. If there is no air resistance, when they hit the ground a. both will have the same kinetic energy b. the heavier one will have twice the kinetic energy of the lighter one c. the heavier one will have four times the kinetic energy of the lighter one d. the heavier one will have half the kinetic energy of the lighter one e. the heavier one will have one-fourth the kinetic energy of the lighter one

b. the heavier one will have twice the kinetic energy of the lighter one

Which two temperature increments are equivalent? a. 1 K = 1 F b. 1 F = 1 C c. 1 C = 1 K d. none of the above

c. 1 C = 1 K

A 75 W incandescent bulb produces 3.0 W of visible-light energy. What is the efficiencies of the bulb for converting electric energy into light? a. 75% b. 3% c. 4% d. 25 %

c. 4%

When you drop a pebble from height H, it reaches the ground with speed V if there is no air resistance. From what height should you drop it so it will reach the ground with twice speed? a. 1H b. 2H c. 4H d. 8H e. 16H

c. 4H

Describe the type(s) of energy of a car driving up a hill. a. the energy is entirely kinetic energy b. the energy is entirely potential energy c. it has both kinetic and potential energy d. it is gravitational

c. it has both kinetic and potential energy

When atmospheric pressure increases, what happens to the absolute pressure at the bottom of a pool? a. it does not change b. it increases by the same amount c. it increases by the same amount d. it increases by a greater amount

c. it increases by the same amount

A heavy lead block and a light aluminum block of equal sizes are both submerged in water. Upon which is the buoyant force greater? a. on the lead block b. on the aluminum block c. they both experience the same buoyant force

c. they both experience the same buoyant force

If you push twice as hard against a stationary brick wall, the amount of work you do a. doubles b. is cut in half c. remains constant but non-zero d. remains constant at zero

d. remains constant at zero

We measure the energy in food by measuring a. its volume b. its mass c. its density d. the amount of heat released when burning

d. the amount of heat released when burning

The quantity Fd/t is a. the kinetic energy of the object b. the potential energy of the object c. the work done on the object by the force d. the power supplied to the object by the force

d. the power supplied to the object by the force

A machine uses 1000 J of electric energy to raise a heavy mass, increasing its potential energy by 300 J. What is the efficiency of this process? a. 100% b. 85% c. 70% d. 35% e. 30%

e. 30%

Jill does twice as much work as Jack does and in half the time. Jill's power output is a. the same as Jack's power output b. one-fourth as much as Jack's power output c. one-half as much as Jack's power output d. twice Jack's power output e. four times Jack's power output

e. four times Jack's power output

Consider a brick that is suspended and totally immersed in water, with the long edge of the brick vertical. The pressure on the brick is a. the same on all surfaces of the brick b. greatest on the face with largest area c. greatest on the top of the brick d. greatest on the sides of the brick e. greatest on the bottom of the brick

e. greatest on the bottom of the brick

An object moving faster than the earth's escape velocity (about 11 km/s) has enough energy to escape the pull of the earth's gravity. Which of the following gas molecules would be most likely to be moving at a speed high enough to escape the earth's atmosphere? (Assume the same temperature.) a. carbon dioxide b. oxygen c. nitrogen d. water vapor e. hydrogen

e. hydrogen

When you throw a pebble straight up with initial speed V, it reaches a maximum height H with no air resistance. At what speed should you throw it up vertically so it will go twice as high? a. 16V b. 18V c. 4V d. 2V e. sqrt (2) V

e. sqrt (2) V