Chapter 6: Work, Energy, and Energy Resources - Review Questions

What is the scientific definition of work?

a) The product of force and displacement in the direction of the force

b) The product of force and time

c) The sum of force and displacement

d) The difference between force and displacement

a) The product of force and displacement in the direction of the force

What is the unit of work in the SI system?

a) Joule

b) Newton

c) Watt

d) Pascal

a) Joule

When is the work done by a force considered negative?

a) When the force is in the opposite direction to the displacement

b) When the force is perpendicular to the displacement

c) When the force is in the same direction as the displacement

d) When there is no displacement

a) When the force is in the opposite direction to the displacement

Work is defined as the product of the component of the force in the direction of motion times the ___ through which the force acts.

distance

What is the relationship between net work and kinetic energy according to the work-energy theorem?

a) Net work equals the change in kinetic energy

b) Net work is half the change in kinetic energy

c) Net work is double the change in kinetic energy

d) Net work is unrelated to kinetic energy

a) Net work equals the change in kinetic energy

Which of the following is the correct expression for translational kinetic energy?

a) KE = 1/2 mv^2

b) KE = mv^2

c) KE = 1/2 mv

d) KE = mv

a) KE = 1/2 mv^2

What happens to the kinetic energy of an object if its speed is doubled?

a) It quadruples

b) It doubles

c) It remains the same

d) It halves

a) It quadruples

The work-energy theorem states that the net work done on a system equals the change in the quantity ___.

of the kinetic energy

Translational kinetic energy is defined as KE = ___.

1/2 mv^2

What happens to gravitational potential energy when an object is lifted to a higher position?

a) It increases

b) It decreases

c) It remains constant

d) It becomes zero

a) It increases

How does gravitational potential energy relate to kinetic energy when an object falls?

a) Potential energy is converted to kinetic energy

b) Kinetic energy is converted to potential energy

c) Both energies remain constant

d) Both energies are lost

a) Potential energy is converted to kinetic energy

What is the significance of choosing a reference level for gravitational potential energy?

a) It determines the absolute value of potential energy

b) It affects the difference in potential energy

c) It changes the mass of the object

d) It alters the gravitational force

b) It affects the difference in potential energy

Why is it easier to use potential energy rather than work to solve problems?

a) Potential energy calculations are simpler

b) Work calculations are more accurate

c) Potential energy is always constant

d) Work is not related to energy

a) Potential energy calculations are simpler

The work done against gravity when lifting an object is stored as ___.

gravitational potential energy

The change in gravitational potential energy is given by the formula ___.

ΔPEg = mgh

What is a conservative force?

a) A force for which work done depends on the path taken

b) A force for which work done depends only on the starting and ending points

c) A force that always does positive work

d) A force that cannot store energy

b) A force for which work done depends only on the starting and ending points

What is the potential energy stored in a spring that is compressed by a distance x?

a) PE = kx

b) PE = 1/2 kx^2

c) PE = kx^2

d) PE = 1/2 kx

b) PE = 1/2 kx^2

Which of the following is true about mechanical energy in a system with only conservative forces?

a) Mechanical energy is always increasing.

b) Mechanical energy is always decreasing.

c) Mechanical energy is conserved.

d) Mechanical energy is converted to thermal energy.

c) Mechanical energy is conserved.

The potential energy of a spring is given by the formula PEs = ___.

1/2 kx^2

A conservative force is one for which work done depends only on the ___ and ___ points of a motion.

starting; ending

What is a characteristic of nonconservative forces?

a) They depend on the path taken.

b) They are associated with potential energy.

c) They do not affect mechanical energy.

d) They are always conservative.

a) They depend on the path taken.

How does friction affect mechanical energy in a system?

a) It converts mechanical energy into potential energy.

b) It adds mechanical energy to the system.

c) It removes mechanical energy from the system.

d) It does not affect mechanical energy.

c) It removes mechanical energy from the system.

What does the work-energy theorem state when both conservative and nonconservative forces act?

a) The net work equals the change in potential energy.

b) The net work equals the change in kinetic energy.

c) The net work equals the sum of potential and kinetic energy.

d) The net work equals zero.

b) The net work equals the change in kinetic energy.

What happens to mechanical energy when nonconservative work is positive?

a) Mechanical energy decreases.

b) Mechanical energy remains constant.

c) Mechanical energy increases.

d) Mechanical energy is converted to potential energy.

c) Mechanical energy increases.

A nonconservative force is one for which work depends on the ___.

path

The work done by nonconservative forces equals the change in the ___ energy of a system.

mechanical

What does the law of conservation of energy state?

a) Total energy is constant in any process.

b) Energy can be created or destroyed.

c) Energy can only be transferred, not transformed.

d) Energy is only conserved in closed systems.

a) Total energy is constant in any process.

Which of the following is NOT a form of energy mentioned in the text?

a) Chemical energy

b) Thermal energy

c) Gravitational energy

d) Sound energy

d) Sound energy

What is the efficiency of a coal power plant as mentioned in the text?

a) 20%

b) 35%

c) 42%

d) 98%

c) 42%

The law of conservation of energy states that total energy is ___ in any process.

constant

Efficiency is defined as the ratio of useful energy or work output to total energy ___.

input

Describe the problem-solving strategy for energy when dealing with nonconservative forces.

When dealing with nonconservative forces, use the general conservation of energy equation: KEi + PEi + Wnc + OEi = KEf + PEf + OEf, where Wnc is the work done by nonconservative forces.

What is the scientific definition of power?

a) The rate at which work is done

b) The amount of work done

c) The force applied over a distance

d) The energy stored in an object

a) The rate at which work is done

What is the SI unit for power?

a) Joule

b) Watt

c) Newton

d) Pascal

b) Watt

How much energy does a 60-W light bulb expend per second?

a) 60 J

b) 120 J

c) 30 J

d) 600 J

a) 60 J

What is the power output of a person at rest?

a) 100 W

b) 60 W

c) 8 W

d) 3 W

a) 100 W

Which of the following devices has the highest power consumption?

a) Electric clock

b) Pocket calculator

c) Clothes dryer

d) Heart at rest

c) Clothes dryer

The formula for power is given by P = __ / t.

W

The energy consumed over a time period is calculated using the formula E = __ x t.

P

What is the basal metabolic rate (BMR)?

a) The rate at which the body uses energy at rest

b) The rate at which the body uses energy during exercise

c) The total energy consumed in a day

d) The energy required to perform useful work

a) The rate at which the body uses energy at rest

Which organ consumes the most power at rest according to Table 7.4?

a) Brain

b) Liver & spleen

c) Heart

d) Kidney

b) Liver & spleen

How much energy is produced per liter of oxygen consumed?

a) 10 kJ

b) 20 kJ

c) 30 kJ

d) 40 kJ

b) 20 kJ

What is considered 'useful work' in the context of human energy expenditure?

a) Work done by the heart

b) Work done in climbing stairs

c) Work done by the digestive system

d) Work done by the liver

b) Work done in climbing stairs

The basal metabolic rate (BMR) is the total energy conversion rate of a person at ___.

rest

Approximately ___ kJ of energy are produced for each liter of oxygen consumed.

20

How does exercise contribute to weight loss in terms of energy consumption?

Exercise increases energy expenditure, which can lead to weight loss if the energy consumed through food is less than the energy expended. The body uses stored fat to make up for the energy deficit, resulting in fat loss.

What percentage of the world's energy comes from nonrenewable fossil fuels?

a) 85%

b) 50%

c) 30%

d) 15%

a) 85%

Which country surpassed the United States as the largest generator of CO2 in 2009?

a) India

b) China

c) Russia

d) Brazil

b) China

What is a major benefit of diversifying energy sources through renewables?

a) Increased dependency on fossil fuels

b) Higher vulnerability to natural disasters

c) Faster recovery from energy disruptions

d) Decreased employment opportunities

c) Faster recovery from energy disruptions

Renewable energy sources include water, wind, solar, and ___.

biomass

In 2003, China surpassed Japan as the world's second largest consumer of ___.

oil

Why is energy conservation important despite the law of conservation of energy?

Energy conservation is important because the final result of most energy transformations is waste heat transfer to the environment and conversion to energy forms no longer useful for doing work. This degradation of energy potential makes it necessary to conserve energy resources.

How does economic well-being relate to energy use?

Economic well-being is dependent upon energy use, with higher standards of living typically matched by higher levels of energy consumption per capita. Increased efficiency of energy use can change this dependency.