Physics 011
MC#6
Chapter 6: Work and Energy

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.) 


5
J 


10
J 


49
J 


200
J 




The derived unit for energy and work is called the joule, J. It is equivalent to which combination of SI units? 


kg
m^{2} 


N/m^{2} 


kg
m^{2}/s^{2} 


W/N 




Work is done when a force



I
and II only 


II
and IV only 


I
only 


III
only 




If the velocity of a body is doubled, its kinetic energy 


decreases
to half its original value. 


increases
to two times its original value. 


decreases
to one fourth its original value. 


increases
to four times its original value. 




What is the kinetic energy of a 10.0kg mass with a velocity of 2.00 m/s? 


20
J 


10
J 


5
J 


2.5
J 




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? 


Cart
A has the greater kinetic energy. 


Cart
B has the greater kinetic energy. 


Cart
A has the greatest acceleration. 


Cart
B has the greater acceleration. 




If the speed at which a car is traveling is tripled, by what factor does its kinetic energy increase? 


3^{1/2} 


3 


6 


9 




Work is measured in the same units as 


force. 


energy. 


momentum. 


power. 




What happens to the speed of a body if its kinetic energy is doubled? 


It
is multiplied by 2^{1/2}. 


It
is doubled. 


It
is halved. 


It
is multiplied by 4. 




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}. 


less
than 


more
than 


equal
to 


incomparable
with 




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}. 


more
than 


less
than 


equal
to 


incomparable
with 




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 __________. 


1 


1/2 


2 


1/3 


3 


1/4 




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 ___________. 


1 


1/2 


2 


1/3 


3 


4 




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 ____________. 


1 


1/2 


2 


1/3 


3 


1/4 




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 ___________. 


1 


1/2 


2 


1/3 


3 


1/4 




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? 


0
J 


49
J 


98
J 


196
J 




How much work must be done to raise a 5.0kg block of steel from the ground to a height of 2.0 m? 


2.5
N 


10
N 


49
N 


98
N 




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? 


0
J 


2
J 


20
J 


50
J 




The work done in raising a body must 


increase
the kinetic energy of the body. 


decrease
the total mechanical energy of the body. 


decrease
the internal energy of the body. 


increase
the gravitational potential energy of the body. 




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? 


100
J 


150
J 


200
J 


250
J 




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? 


70
J 


147
J 


280
J 


343
J 




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 __________. 


x_{1}
> x_{2} > x_{3} 


x_{1}
< x_{2} < x_{3} 


x_{1}
= x_{2} = x_{3} 


none
of these 




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 __________. 


EPE_{1}
< EPE_{2} < EPE_{3} 


EPE_{1}
= EPE_{2} = EPE_{3} 


EPE_{1}
> EPE_{2} > EPE_{3} 


none
of these 




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 ____________. 


1 


2 


3 


4 


5 




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
____________. 


1 


3 


5 


9 


some
other value 




The total energy of a body free falling in a vacuum 


increases. 


decreases. 


remains
the same. 


depends
on the shape of the body. 




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 ___________. 


1 


2 


3 


4 


6 




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}. 


less
than 


equal
to 


more
than 


incomparable
with 




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 ____________. 


1 


2 


1/2 


3 


1/3 


4 




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 ____________. 


1 


2 


1/2 


3 


1/3 


4 




The rate at which work is being done is 


energy. 


power. 


momentum. 


force. 




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? 


50
W 


500
W 


5000
W 


50000
W 




What is the average power output of a 50kg boy who climbs a 2.0m step ladder in 10 seconds? 


10
W 


49
W 


98
W 


250
W 




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? 


5
N 


50
N 


500
N 


5000
N 




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? 


0.05
m/s 


0.02
m/s 


20
m/s 


50
m/s 




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
power developed by A is the same as that of B. 


The
power developed by A is half that of B. 


The
power developed by A is twice that of B. 


The
power developed by A is 4 times that of B. 
