Life Science Chapter 3 Energy

Work is the rate at which you expend energy.

False

The energy an object has because of its position is called potential energy.

True

The increase in potential energy caused by lifting an object can be calculated by multiplying its weight by its change in height.

True

Your electric bill for 1500 kilowatt-hours is a charge for the power you have used that month.

False

You do more work on yourself when you run up the stairs than when you walk slowly.

False

Plants convert radiant energy from the sun into chemical energy by a process called photosynthesis.

True

An object that falls twice as far will be moving twice as fast when it hits the ground.

False

As we deplete our coal reserves, we can replace this lost source of energy by increasing our output of hydroelectric power.

False

Energy is not conserved when a moving object slows to a stop.

False

Nearly all of the energy consumed today is provided by petroleum, coal, hydropower and nuclear sources.

True

A spring-loaded paper clamp exerts a force of 2 N on 10 sheets of paper it is holding tightly together. Is the clamp doing work as it holds the papers together?

No

The watt (W) is a unit of

A. work

B. electrical energy

C power

D. force

C. power

What are the units for the work of done by a newton of force acting through a meter of distance?

A. joule

B. ft-lb

C. horsepower

D. watt

A. joule

Which one of the following has an appropriate unit?

A. work-joule

B. force-newton

C. power-watt

D. all of the above

D. all of the above

Which one of the following does NOT have the same units as the others?

A. kinetic energy

B. momentum

C. potential energy

D. work

B. momentum

A car is traveling twice as fast as an identical car. How much more work will be needed to stop the car traveling twice as fast?

A. same

B. twice as much

C. four times as much

D. nine times as much

C. four times as much

When a light bulb is rated at 60 W, it means that

A. the bulb uses 60 J of power when it is lit

B. current is traveling at 60 m/s through the filament

C.each second, the bulb converts 60 J of electrical energy to heat and light

D. the bulb loses 60 W of potential energy each second

C. each second, the bulb converts 60 J of electrical energy to heat and light

Kinetic energy refers to

A. energy of motion

B. energy of position

C.energy stored in fossil fuels

D. electrical energy

A. energy of motion

When you throw a ball into the air, it's kinetic energy

A. equals 1/2 mv^2

B.equals the work you did on the ball when you threw it

C. if converted to potential energy as it goes higher+

D. all of the above

D. all of the above

A flower pot falls off a window ledge 10 m above the ground. Its kinetic energy as it hits the ground is

A. the same as the potential energy it had before falling

B. equal to the work done in placing the pot on the ledge

C. equal to the loss of potential energy as a result of the fall

D. all of the following

D. all of the above

The important variables in gravitational potential energy are the weight of an object and the

A. distance to the floor

B. height above the Earth's surface

C. change of position

D. none of the above

C. change of position

Two students stand poised to leap off a high dive structure into the swimming pool below. Student B is twice as massive as student A. Which of the following is true?

A. student B will reach the ground sooner than student A

B. both students have the same gravitational potential energy

C. Both students will have the same kinetic energy just before impact

D. student B did twice as much work climbing to the top of the structure

D. student B did twice as much work climbing to the top of the structure

Roughly, what fraction of the USA's current energy needs is supplied by coal

A. 10%

B. 20%

C. 40%

D. 50%

B. 20%

While exploring an ancient Mayan tomb, you discover that the walls are closing in on you. By exerting 400 N of force, you are able to keep the wall from coming closer. The work you are doing on the wall is

A. 400 J

B. 3920 J

C. unknown, because the mass of the wall is not given

D. zero, because the wall is not moving

D. zero, because the wall is not moving

The rate at which work is done is

A. power

B. momentum

C. potential energy

D. kinetic energy

A. power

A pendulum is pulled back to position a, then released. Where is its kinetic energy the maximum?

A. a

B. b

C. c

D. d

C. c

Which of the following energy sources does NOT exist on or under Earth's surface?

A. coal

B. hydropower

C. hydrogen

D. none of the above

C. hydrogen

The smallest available geothermal resource is

A. steam

B. hot water

C. the hot, dry rocks

D. geopressurized reservoirs

A. steam

Which of the following is NOT a solar technology?

A. biomass

B. wind

C. geothermal hot water

D. power tower

C. geothermal hot water

An abundant but dirty energy source is

A. geothermal hot water

B. coal

C. nuclear

D. petroleum

A. geothermal hot water

Which of the following is a renewable energy source?

A. petroleum

B. coal

C. biodiesel

D. natural gas

C. biodiesel

Which energy source produces no pollutants?

A. hydrogen

B. nuclear

C. geothermal steam

D. natural gas

A. hydrogen

According to PE= mgh, gravitational potential energy is the same thing as

A. exerting a force through a distance in any direction

B. the kinetic energy an object had before coming to a rest

C. work against a vertical change of position

D. the momentum of a falling object

C. work against a vertical change of position

Two cars have the same mass, but one is moving three times as fast as the other is. How much more work will be needed to stop the faster car?

A. the same amount

B. twice as much

C. three times as much

D. nine times as much

D. nine times as much

Kinetic energy can be measured in terms of

A. work done on an object to put it into motion

B. work done on a moving object to bring it to rest

C. either a or b

D. neither a or b

C. either a or b

Potential and kinetic energy are created when work is done to change a position (PE) or a state of motion (KE). Ignoring friction how does the amount of work done to make the change compare to the amount of PE or KE created?

A. less energy is created

B. Both are the same

C. more energy is created

D. this cannot be generalized

B. both are the same

Which path would result in more work accomplished in moving a box to the same spot on a table?

A. a

B. b

C. c

D. all would be equal

D. all would be equal

The force exerted when doing work by lifting an object against gravity is measured in units of

A. kg

B. N

C. W

D. J

B. N

The work accomplished by lifting an object against is measured in units of

A. kg

B. N

C. W

D. J

D. J

A unit of power is the

A. ft-lb

B. N

C. Nm

D. Nm/s

D. Nm/s