MasteringPhysics: Assignment Print View
http://session.masteringphysics.com/myct/assignmentPrint?assignm.
..
1 of 11
10/11/08 11:40 PM
[
Print View
]
Physics 2211001, Fall 2008
Work
Due at 11:00pm on Wednesday, September 24, 2008
View Grading
Details
Introduction to Potential Energy
Learning Goal:
Understand that conservative forces can be removed from the work integral by incorporating them
into a new form of energy called potential energy that must be added to the kinetic energy to get the total mechanical
energy.
The first part of this problem contains shortanswer questions that review the workenergy theorem. In the second part
we introduce the concept of potential energy. But for now, please answer in terms of the workenergy theorem.
WorkEnergy Theorem
The workenergy theorem states
,
where
is the work done by
all
forces that act on the object, and
and
are the initial and final kinetic
energies, respectively.
Part A
The workenergy theorem states that a force acting on a particle as it moves over a ______ changes the ______
energy of the particle.
Choose the best answer to fill in the blanks above:
ANSWER:
distance / potential
distance / kinetic
vertical displacement / potential
none of the above
Part B
To calculate the change in energy, you must know the force as a function of _______. The work done by the force
causes the energy change.
Choose the best answer to fill in the blank above:
ANSWER:
acceleration
work
distance
potential energy
Part C
[
Print
]
This preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentMasteringPhysics: Assignment Print View
http://session.masteringphysics.com/myct/assignmentPrint?assignm.
..
2 of 11
10/11/08 11:40 PM
To illustrate the workenergy concept, consider the case of a stone falling from
to
under the influence of
gravity.
Using the workenergy concept, we say that work is done by the gravitational _____, resulting in an increase of the
______ energy of the stone.
Choose the best answer to fill in the blanks above:
ANSWER:
force / kinetic
potential energy / potential
force / potential
potential energy / kinetic
Potential Energy
You should read about potential energy in your text before answering the following questions.
Potential energy
is a concept that builds on the workenergy theorem, enlarging the concept of energy in the most
physically useful way. The key aspect that allows for potential energy is the existence of conservative forces, forces
for which the work done on an object does not depend on the path of the object, only the initial and final positions of
the object. The gravitational force is conservative; the frictional force is not.
The change in potential energy is the
negative
of the work done by conservative forces. Hence considering the initial
and final potential energies is equivalent to calculating the work done by the conservative forces. When potential
energy is used, it
replaces the work
done by the associated conservative force. Then only the work due to
nonconservative
forces needs to be calculated.
In summary, when using the concept of potential energy, only
This is the end of the preview.
Sign up
to
access the rest of the document.
 Fall '08
 DUNCAN
 Force, Kinetic Energy, Potential Energy, Work, Assignment Print View

Click to edit the document details