90 Questions
Which type of energy is stored in a deformed spring?
Potential energy
What does an energy bar chart represent?
The amount of energy of a given type in the system
When a spring is undeformed, its elastic potential energy is
Zero
Which form of energy is being transformed into internal energy as the book slows down due to friction?
Kinetic energy
Where does the energy go when a nonconservative force does work on a surface?
Internal energy
What is the value of the kinetic energy after the book has stopped sliding?
Zero
What happens to the kinetic energy of a system when a nonconservative force acts on it?
It becomes zero
What does the total energy bar in red represent in Figure 7.18d?
Total mechanical energy
What does the system contain after the book has stopped sliding?
Only internal energy
What is the relationship between the amount of internal energy and the amount of kinetic energy after the book has stopped?
They are equal
According to the text, what is the formula for kinetic energy?
$K = \frac{1}{2}mv^2$
Which of the following is true about work done on a system?
It changes the system's speed
What is the net work done on a particle of mass $m$ equal to?
$1/2 mv^2$
What does the equation $W_{ext} = \frac{1}{2}mv_f^2 - \frac{1}{2}mv_i^2$ represent?
The change in kinetic energy of a block
What is the special name given to the quantity $\frac{1}{2}mv^2$?
Kinetic energy
Which of the following statements is true about kinetic energy?
Kinetic energy is directly proportional to mass.
Which equation represents the work-kinetic energy theorem?
$W_{ext} = K_f - K_i$
When is the net work done on a system positive?
When the final kinetic energy is greater than the initial kinetic energy.
Which type of motion does the work-kinetic energy theorem also apply to?
Rotational motion
What does the work-kinetic energy theorem tell us about the net work done on a system?
The net work done on a system is equal to the change in kinetic energy.
Which equation describes the gravitational potential energy of an object of mass m and the Earth?
$U_g = mgy$
What is the unit of gravitational potential energy?
Joules
Which equation describes the elastic potential energy of a block-spring system?
$U_s = \frac{1}{2}kx^2$
What is the force exerted by a spring on a block in a block-spring system?
$F_s = 2kx$
What is the work done on a block-spring system by an applied force?
$W_{ext} = \frac{1}{2}k(x_f^2 - x_i^2)$
According to the work-kinetic energy theorem, when work is done on a system, the result is a transfer of energy across the boundary of the system. What is the result on the system, in the case of Equation 7.17?
A change in kinetic energy
A dart is inserted into a spring-loaded dart gun by pushing the spring in by a distance x. For the next loading, the spring is compressed a distance 2x. How much faster does the second dart leave the gun compared with the first?
Four times as fast
In the context of potential energy, what is the energy storage mechanism before an object is released?
Potential energy
In the context of potential energy, what determines the amount of potential energy in a system?
The type of force acting between members of the system
When an object is lifted from an initial height yi to a final height yf above the surface of the Earth, what is the work done by the external agent on the system (object and the Earth)?
mg(yf - yi)
Kinetic energy is a scalar quantity.
True
The units of kinetic energy are the same as work.
True
Equation 7.17 represents the work-kinetic energy theorem.
True
The net work done on a system equals the change in kinetic energy of the system.
True
The work-kinetic energy theorem is valid for both translational and rotational motion.
True
True or false: Work is a mechanism for transferring energy into a system?
True
True or false: Kinetic energy is a type of energy that a system can possess?
True
True or false: The work done on a block by an external net force is equal to the difference between the initial and final values of the quantity 1/2 mv^2?
True
True or false: The equation 1/2 mv^2 represents the kinetic energy of an object?
True
True or false: The work-kinetic energy theorem states that the net work done on a system is equal to the change in kinetic energy of the system?
True
Gravitational potential energy only depends on the vertical height of the object above the surface of the Earth.
True
The choice of reference configuration for zero gravitational potential energy is completely arbitrary.
True
The work done on a block-spring system is given by the equation $W_{ext} = \Delta U_s$.
True
The force that a spring exerts on a block is given by the equation $F_s = 2kx$.
True
The elastic potential energy function associated with a block-spring system is defined by the equation $U_s = \ rac{1},{2}kx^2$.
True
True or false: When work is done on a system, energy is transferred across the boundary of the system?
True
True or false: The kinetic energy of a system consisting of two or more particles is the sum of the kinetic energies of all members of the system?
True
True or false: The potential energy of a system can only be associated with specific types of forces acting between members of the system?
True
True or false: The amount of potential energy in a system is determined by the configuration of the system?
True
True or false: The work done on a system by an external agent can be calculated using the equation $W_{ext} = mgy_f - mgy_i$?
True
True or false: Elastic potential energy is stored in a deformed spring.
True
True or false: Energy bar charts are a useful representation for keeping track of the various types of energy in a system.
True
True or false: The energy associated with the temperature of a system is called internal energy.
True
True or false: The nonconservative force between the book and the surface in Figure 7.18a transforms the kinetic energy of the system into internal energy.
True
True or false: When a nonconservative force does work on a surface, the energy is transferred into the system as internal energy.
True
True or false: The kinetic energy of the book transforms into internal energy as it slows down due to friction.
True
True or false: After the book has stopped sliding, the kinetic energy is zero and the system contains only internal energy.
True
True or false: The total energy bar in red changes during the process.
False
True or false: The amount of internal energy in the system after the book has stopped is equal to the amount of kinetic energy.
True
True or false: The amount of internal energy in the system after the book has stopped is greater than the amount of kinetic energy.
False
What is the equation for calculating the net work done on a block?
$W_{ext} = \ rac{1}{2}mv_f^2 - \ rac{1}{2}mv_i^2$
What is the formula for kinetic energy?
$K = \ rac{1}{2}mv^2$
What is the result of doing work on a system?
The system changes its speed
What is the special name given to the quantity $\ rac{1}{2}mv^2$?
Kinetic energy
What does the work-kinetic energy theorem state?
The net work done on a system is equal to the change in kinetic energy of the system
What is the relationship between the amount of internal energy and the amount of kinetic energy after the book has stopped?
The amount of internal energy after the book has stopped is equal to the amount of kinetic energy.
What does the total energy bar in red represent in Figure 7.18d?
The total energy bar in red represents the unchanged total energy of the system.
True or false: The amount of internal energy in the system after the book has stopped is greater than the amount of kinetic energy.
False
Which form of energy is being transformed into internal energy as the book slows down due to friction?
Kinetic energy
What does the system contain after the book has stopped sliding?
The system contains only internal energy
What is the equation for gravitational potential energy?
$U_g = mgy$
What is the equation for elastic potential energy?
$U_s = \frac{1}{2}kx^2$
What is the equation for the net external work done on a system in terms of the change in gravitational potential energy?
$W_{ext} = \Delta U_g$
What is the equation for the net external work done on a block-spring system in terms of the change in elastic potential energy?
$W_{ext} = \Delta U_s$
What does the work-kinetic energy theorem describe?
The relationship between the net work done on a system and the change in kinetic energy of the system
What is the formula for calculating the amount of internal energy in a system?
The formula for calculating the amount of internal energy in a system is E_{ ext{int}}.
What is the work done on a system by an external agent equal to?
The work done on a system by an external agent is equal to the change in the system's internal energy.
What happens to the kinetic energy of a system when a nonconservative force acts on it?
When a nonconservative force acts on a system, the kinetic energy of the system is transformed into internal energy.
What does the work-kinetic energy theorem state?
The work-kinetic energy theorem states that the net work done on a system is equal to the change in the system's kinetic energy.
What is the unit of gravitational potential energy?
The unit of gravitational potential energy is joules (J).
Which equation represents the work done by an external agent on a system consisting of an object and the Earth, as the object is lifted from an initial height $y_i$ to a final height $y_f$ above the ground?
True
What is the energy storage mechanism before an object is released and falls due to gravity?
True
What is the work done by an external agent on a system (object and the Earth) as the object is lifted from an initial height $y_i$ to a final height $y_f$ above the ground?
$mgy_f - mgy_i$
What determines the amount of potential energy in a system?
the configuration of the system
When an object is lifted from an initial height $y_i$ to a final height $y_f$ above the surface of the Earth, what is the work done by the external agent on the system (object and the Earth)?
$mgy_f - mgy_i$
What is kinetic energy and how is it related to work?
Kinetic energy represents the energy associated with the motion of a particle. It is a scalar quantity and has the same units as work. The work-kinetic energy theorem states that the work done on a particle by a net force equals the change in kinetic energy of the particle.
What is the work-kinetic energy theorem and what does it tell us?
The work-kinetic energy theorem states that when work is done on a system and the only change in the system is in its speed, the net work done on the system equals the change in kinetic energy of the system. It tells us that the speed of a system increases if the net work done on it is positive, and decreases if the net work is negative.
How is the work-kinetic energy theorem applicable to rotational motion?
The work-kinetic energy theorem is also valid for systems that undergo a change in rotational speed due to work done on the system. It applies to situations where an object spins about an axis.
What is the significance of the net work being zero in the case of a spring pushing a block?
In the case of a spring pushing a block from maximum compression to maximum extension, the net work done on the block is zero. This is because the speed of the block is zero at both the initial and final points of the motion. The work-kinetic energy theorem only refers to the initial and final points for the speeds, and does not depend on the details of the path followed between these points.
How does the work done by different forces affect the net work done on an object?
The net work done on an object is found by adding up the works done by each force and adding. This is valid as long as the net work is found by adding up the works done by each force and adding, as discussed earlier with regard to Equation 7.8. The work-kinetic energy theorem is an important result that indicates the transfer of energy into a system through work.
"Quiz: Understanding Work and Potential Energy in Physics" Test your knowledge of work and potential energy with this quiz. Explore the concepts of energy transfer, kinetic energy, and gravitational potential energy in a system. Challenge yourself to identify different forms of energy and their equations.
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