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.
