4.2.1 The Work-Kinetic Energy Theorem Flashcards
The Work-Kinetic Energy Theorem
- Energy is the capacity to do work.
- Anything that is moving can do work.•Kinetic energy is the energy of motion: .
- The work-kinetic energy theorem relates work to the change in kinetic energy:
An object at rest on a table is given an initial push. The object starts moving and has some initial kinetic energy. The object slows down and eventually comes to rest. According to the work-kinetic energy theorem, work done on the object causes change in its kinetic energy, delta K. In this case, the work is done by the force of friction. Which of the following is the nature of the work done by friction on the object?
Friction does negative work on the object.
Which of the following expresses the work-kinetic energy theorem?
Wnet = Kf - Ki
sigma W = delta K
How is the kinetic energy of an object affected if its velocity is doubled?
The kinetic energy is quadrupled.
In kinematics, the final velocity vf of an object undergoing constant acceleration is given by which of the following equations?
vf^2 = vi^2 + 2ax delta x
Evaluate the following as true or false.
The work-kinetic energy theorem can be derived fro the special case of a constant force in one dimension. The result obtained is given by
Wnet = 1/2mvf^2 - 1/2mvi^2
This equation describes the work-kinetic energy relationship fro only the special case of constant force
false
If the net work done on an object is negative, which of the following expresses the relationship between the final velocity vf and the initial velocity vi?
vf < vi
Evaluate the following as true or false.
A force F does positive work on two object A and B along the displacement delta x. Suppose both F and delta x are the same for the two objects. Therefore, for both A and B the changes in velocity delta vA and delta vB are necessarily equal.
false
