Science Test 2

A 2-kg book is held 1 m above the floor for 50 s. The work done is

0

a) How much work is done in moving a 1.1 kg book to a shelf 1.30 m high? J (b) What is the change of potential energy of the book as a result? J (c) How much kinetic energy will the book have as it hits the ground when it falls? J

14.014

How much work is needed to stop a 1,310 kg car that is moving straight down the highway at 64.0 km/h? × 10 J

2.08 5th power

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

20%

A 166.0 lb student runs up a stairway to a classroom 20.0 ft above ground level in 11.0 s. (a) How much work did the student do? ft·lb (b) What was the average power output in hp? hp

3320 0.549

A 1,000 kg car stops on top of a 57.44 m hill. How much energy was used in climbing the hill? How much potential energy does the car have? Energy used = J; Potential Energy = J

600,000

horizontal force of 10 lb is needed to push a bookcase 7.3 ft across the floor. (a) How much work was done on the bookcase? (b) How much did the gravitational potential energy change as a result? a) W = ft·lb (b) ΔPE = ft·lb

73 0

55.3−kg student runs up a 6.00−m high stairway in a time of 4.15 seconds. How many watts of power did she develop? How many horsepower is this (round to the nearest whole number)? W Horsepower

784 1

When you throw a ball into the air, its kinetic energy equals1/2 mv2 . equals the work you did on the ball. is converted to potential energy as it goes higher. All of the above.

All

The potential energy of a box on a shelf, relative to the floor, is a measure of the weight of the box times the distance above the floor any of these the work done putting the box on the shelf from the floor the energy the box has because of its position above the floor

Any of these

Which of the following is a renewable energy source?

Biodiesel

An abundant but dirty energy source is

Coal

T/F: A spring-loaded paper clamp exerts a force of 2 N on 10 sheets of paper it is holding tightly together. The clamp is doing work as it holds the papers together.

False

T/F: Energy is not conserved when a moving object slows to a stop.

False

T/F: Upon eating food, the chemical energy contained within the food is destroyed by the process of digestion.

False

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

False

In the cylinder of an automobile engine, the chemical energy of gasoline is initially transformed into

Heat energy

Which energy source produces no pollutants?

Hydrogen

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

Momentum

In which of the following energy sources is energy created? none solar nuclear water

None

You can find the kinetic energy of a book of a certain mass just before it hits the floor after falling a certain distance by using which equation?

PE = mgh

The wound spring of a watch possesses _______________ energy.

Potential

A moving object does not necessarily have

Potential energy

The watt (W) is a unit of

Power

The watt is a unit of

Power

Radiant energy can be coverted into electrical energy using

Solar cells

A golf ball and a ping-pong ball are dropped in a vacuum chamber. When they have fallen halfway down, they have the same

Speed

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? Both students will have the same kinetic energy just before impact Student B will reach the ground sooner than student A. Both students have the same gravitational potential energy. Student B did twice as much work climbing to the top of the structure.

Student B did twice as much work

T/F: Farmer Ben attempts to remove an 80-kg rock from his field. If he applies a force of 789 N for 10 seconds yet fails to move the rock, he has done no work.

True

TRUE or FALSE: Simple machines work for you by making it possible to apply a small force over a large distance to get a large force working over a small distance.

Truw

An unsolved problem for nuclear energy is

Waste disposal

Solar radiation is ultimately responsible for

Wind energy

A flower pot falls off a window ledge 10 m above the ground. Its kinetic energy as it hits the ground is: the same as the potential energy it had before falling, equal to the work done in placing the pot on the ledge, equal to the loss of potential energy as a result of the fall, aotb

all of the above

Which one of the following has an appropriate unit? work - joule force - newton power - watt All of the abov

all of the above

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

c - right before reaching the other side

Energy sources used today are mostly in what form of energy?

chemical

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

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

The property that something has that enables it to do work is

energy

Kinetic energy refers to

energy of motion

The law of conservation of energy states:

energy transformations occur without a net gain or loss of energy

The amount of energy released when wood is burned is

equal to the amount of solar energy that was stored by the plant.

Which of the following is not a solar technology? power tower biomass wind geothermal hot water

geothermal hot water

The potential energy of a ball on the ground is zero. If the ball is now in the bottom of a hole, its potential energy is

negative

Which form of energy does not require matter for traveling through space?

radiant

An automobile engine with more power

requires less time to do the same amount of work

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

zero, because the wall is not moving.