1.


How much
work is done when a 0.50kg mass is pushed by a 20N force through a distance
of 10.0 meters? (Assume the force is parallel to the displacement.)
The correct answer: 200 J
See Section 61



2.


The
derived unit for energy and work is called the joule, J. It is equivalent to
which combination of SI units?
The correct answer: kg m^{2}/s^{2}



3.


Work is done when a force
I.
acts
vertically on a box moving along a horizontal surface.
II.
exerted
on one end of a box is equal and opposite to a force exerted on the other end
of the box.
III.
pushes
a box up a frictionless incline.
IV.
of
gravitational attraction acts between a box and the surface of the earth.



4.


If the
velocity of a body is doubled, its kinetic energy
The correct answer:
increases to four times its original value.
See Section 63



5.


What is
the kinetic energy of a 10.0kg mass with a velocity of 2.00 m/s?
The correct answer: 20 J
See Section 63



6.


Cart A has
a mass of 1 kg and a constant velocity of 3 m/s. Cart B has a mass of 1.5 kg
and a constant velocity of 2 m/s. Which statement is true?
The correct answer: Cart A has the greater kinetic energy.



7.


If the
speed at which a car is traveling is tripled, by what factor does its kinetic
energy increase?
The correct answer: 9
See Section 63



8.


Work is
measured in the same units as
The correct answer:
energy.
See Section 63



9.


What
happens to the speed of a body if its kinetic energy is doubled?
The correct answer: It is
multiplied by 2^{1/2}.
See Section 63



10.


An object of mass m_{o}
is initially at rest on a horizontal, frictionless surface. The object is
then subjected to a constant force of magnitude F_{o} which makes an
angle _{o}
with the horizontal as in the figure at the right. After the object has
undergone a horizontal change in displacement D_{o}, it has speed v_{o}
and kinetic energy KE_{o}.
If the angle which the force makes with the horizontal had been slightly
less than _{o},
the speed of the object after the horizontal change in displacement D_{o}
would have been __________ v_{o}.
The correct answer: more than



11.


An object of mass m_{o}
is initially at rest on a horizontal, frictionless surface. The object is
then subjected to a constant force of magnitude F_{o} which makes an
angle _{o}
with the horizontal as in the figure at the right. After the object has
undergone a horizontal change in displacement D_{o}, it has speed v_{o}
and kinetic energy KE_{o}.
If the mass of the object had been slightly more than m_{o}, the
kinetic energy of the object after the horizontal change in displacement D_{o}
would have been __________ KE_{o}.
The correct answer: equal
to
See Section 61, 63



12.


An object of mass m_{o}
is initially at rest on a horizontal, frictionless surface. The object is
then subjected to a constant force of magnitude F_{o} which makes an
angle _{o}
with the horizontal as in the figure at the right. After the object has
undergone a horizontal change in displacement D_{o}, it has speed v_{o}
and kinetic energy KE_{o}.
If the horizontal change in displacement had been 2 D_{o}, the
kinetic energy of the object after this horizontal change in displacement
would have been KE = KE_{o} x __________.
The correct answer: 2
See Section 63



13.


An object of mass m_{o}
is initially at rest on a horizontal, frictionless surface. The object is
then subjected to a constant force of magnitude F_{o} which makes an
angle _{o}
with the horizontal as in the figure at the right. After the object has
undergone a horizontal change in displacement D_{o}, it has speed v_{o}
and kinetic energy KE_{o}.
If the same force continued to act on the object until the speed of the
object was 2 v_{o}, the total distance through which the force would
have acted would be D_{o} x ___________.
The correct answer: 4
See Section 63



14.


If
the work required to get an object with mass m_{o} initially at rest
to a speed v_{o} is W_{o}, . . .
. . . the
additional work required to increase its speed from vo to 2 v_{o}
would be W _{o} x ____________.
The correct answer: 3
See Section 63



15.


If
the work required to get an object with mass m_{o} initially at rest
to a speed v_{o} is W_{o}, . . .
. . . the
work required to get another object with mass 2 m_{o} also initially
at rest to a speed v_{o} would be W_{o} x ___________.
The correct answer: 2
See Section 63



16.


A ball
with a mass of 1.0 kg sits at the top of a 30^{o} incline plane that
is 20.0 meters long. If the potential energy of the ball is 98 J at the top
of the incline, what is its potential energy once it rolls half way down the
incline?
The correct answer: 49 J



17.


How much
work must be done to raise a 5.0kg block of steel from the ground to a
height of 2.0 m?
The correct answer: 98 N
See Sections 61, 64



18.


A
100kilogram box is pulled 10 meters across a frictionless horizontal surface
by a 50N force. What is the change in the potential energy of the box?



19.


The work
done in raising a body must
The correct answer: increase the gravitational potential energy of the
body.
See Section 64



20.


A frictionless incline has a ramp length of 5.0 meters and rises to a
height of 4.0 meters. How much work must be done to move a 50 N box from
bottom to the top of the incline?
The correct answer: 200 J
See Sections 61, 64



21.


A body
located 10.0 meters above the surface of the earth has a gravitational
potential energy of 490 J relative to the ground. What is the gravitational
potential energy, relative to the ground, if the body drops to a height of
7.00 meters above the earth?
The correct answer: 343 J
See Section 64



22.


Three
springs of the same relaxed length L_{o} have spring constants k_{1}
> k_{2} > k_{3}. The springs are
suspended from the ceiling and identical masses are then hung on each of the
springs. In response to these identical stretching forces, the springs
stretch amounts x_{1}, x_{2} and x_{3}, respectively.
The
elongations of the springs are such that __________.
The correct answer: x_{1} < x_{2} <
x_{3}



23.


Three
springs of the same relaxed length L_{o} have spring constants k_{1}
> k_{2} > k_{3}. The springs are
suspended from the ceiling and identical masses are then hung on each of the
springs. In response to these identical stretching forces, the springs
stretch amounts x_{1}, x_{2} and x_{3}, respectively.
The
elastic potential energies stored in each of the three springs are such that
__________.
The correct answer: EPE_{1} < EPE_{2} <
EPE_{3}
See Section 64



24.


The work required to stretch a relaxed spring with
spring constant k_{o} an amount x_{o} is W_{o}.
The
additional work required to stretch the spring from x_{o} to 2 x_{o}
would be W_{o} x ____________.
The correct answer: 3
See Section 64



25.


The work required to stretch a relaxed spring with
spring constant k_{o} an amount x_{o} is W_{o}.
The work required
to stretch the relaxed spring an amount 3 x_{o} would be W_{o}
x ____________.
The correct answer: 9
See Section 64



26.


The total
energy of a body free falling in a vacuum
The correct answer: remains the same.



27.


A block with mass m_{o} on a horizontal,
frictionless surface is tied to one end of a massless spring with spring
constant k_{o} the other end of which is tied to a vertical wall. The
block is pulled aside until the spring has been stretched an amount x_{o},
held at rest and released. When the block passes through its equilibrium
position, its speed is v_{o} and its kinetic energy is KE_{o}.
If the initial stretch of the spring had been 2 x_{o}, the speed
of the block as it passes through its equilibrium position would be v_{o}
x ___________.
The correct answer: 2
See Section 67



28.


A block with mass m_{o} on a horizontal,
frictionless surface is tied to one end of a massless spring with spring
constant k_{o} the other end of which is tied to a vertical wall. The
block is pulled aside until the spring has been stretched an amount x_{o},
held at rest and released. When the block passes through its equilibrium
position, its speed is v_{o} and its kinetic energy is KE_{o}.
If the spring had been stiffer, i.e., k > k_{o}, the speed of
the block as it passed through its equilibrium position would have been
_________ v_{o}.
The correct answer: more
than
See Section 67



29.


A block with mass m_{o} on a horizontal,
frictionless surface is tied to one end of a massless spring with spring
constant k_{o} the other end of which is tied to a vertical wall. The
block is pulled aside until the spring has been stretched an amount x_{o},
held at rest and released. When the block passes through its equilibrium
position, its speed is v_{o} and its kinetic energy is KE_{o}.
If the mass of the block had been 4 m_{o}, the speed of the block
as it passed through its equilibrium position would have been v_{o} x
____________.
The correct answer: 1/2
See Section 67



30.


A block with mass m_{o} on a horizontal,
frictionless surface is tied to one end of a massless spring with spring
constant k_{o} the other end of which is tied to a vertical wall. The
block is pulled aside until the spring has been stretched an amount x_{o},
held at rest and released. When the block passes through its equilibrium
position, its speed is v_{o} and its kinetic energy is KE_{o}.
If the initial stretch of the spring had been 2 x_{o}, the kinetic
energy of the block as it passed through its equilibrium position would have
been KE = KE_{o} x ____________.
The correct answer: 4
See Section 67



31.


The rate
at which work is being done is
The correct answer: power.



32.


What is
the power output by a weight lifter lifting a 10^{3} N weight a
vertical distance of 0.5 meters in 0.1 s?



33.


What is
the average power output of a 50kg boy who climbs a 2.0m step ladder in 10
seconds?
The correct answer: 98 W
See Sections 64, 610



34.


What is
the magnitude of the force exerted by air on a plane if 500 kilowatts of
power are needed to maintain a constant speed of 100 meters per second?
The correct answer: 5000 N



35.


What is
the velocity of a car if its engine is doing work at 100 kW and provides a
constant force of 5.0 x 10^{3} N?
The correct answer: 20
m/s
See Section 610



36.


Two carts
A and B have equal masses. Cart A travels up a frictionless incline with a
uniform velocity that is twice that of Cart B. Which statement is most
accurate?
The correct answer: The
power developed by A is twice that of B.




