Define the work-energy theorem .

The work-energy theorem states that the change in an object's kinetic energy is equal to the sum of the (net) work done by all forces exerted on the object.

The energy dissipated by friction is the friction force multiplied by the .......... of the path over which it acts.

The energy dissipated by friction is the friction force multiplied by the length of the path over which it acts.

When can a system be modeled as a single object, and which energy can then change?

When the system's center of mass and the point of application of the force move the same distance . Only the system's kinetic energy can change.

True or False? If an object's speed is constant, the net work done on it is zero.

True. Its kinetic energy does not change, so by the work-energy theorem the net work is zero. Individual forces can still do positive or negative work.

AP®PhysicsCollege BoardPhysics 1: Algebra-BasedFlashcardsUnit 3: Work, Energy & PowerWork-Energy Theorem

Work-Energy Theorem (College Board AP® Physics 1: Algebra-Based): Flashcards

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FrontWork-Energy Theorem
Define the work-energy theorem.
FrontWork-Energy Theorem
State the equation for the work-energy theorem.
BackWork-Energy Theorem
$∆ K = \sum_{i} W_{i}$
$∆ K$ = change in kinetic energy (J)
$\sum_{i} W_{i}$ = sum of the work done by all forces on the object (N·m)

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Cards in this collection (7)

Define the work-energy theorem.
The work-energy theorem states that the change in an object's kinetic energy is equal to the sum of the (net) work done by all forces exerted on the object.
State the equation for the work-energy theorem.
$∆ K = \sum_{i} W_{i}$
- $∆ K$ = change in kinetic energy (J)
- $\sum_{i} W_{i}$ = sum of the work done by all forces on the object (N·m)
Which component of a force does work on an object?
Only the component of the force parallel to the object's displacement.
$W = F_{∥} d = F d cos θ$
The energy dissipated by friction is the friction force multiplied by the .......... of the path over which it acts.
The energy dissipated by friction is the friction force multiplied by the length of the path over which it acts.
When can a system be modeled as a single object, and which energy can then change?
When the system's center of mass and the point of application of the force move the same distance.
Only the system's kinetic energy can change.
State the equation for the energy dissipated by friction.
$∆ E_{mech} = F_{f} d cos θ$
- $∆ E_{mech}$ = change in mechanical energy (J)
- $F_{f}$ = force of friction (N)
- $d$ = distance moved by the object (m)
- $θ$ = angle between the friction force and the displacement (°)
Friction acts opposite to the displacement, so $θ$ = 180° and $∆ E_{mech}$ is negative.
True or False?
If an object's speed is constant, the net work done on it is zero.
True.
Its kinetic energy does not change, so by the work-energy theorem the net work is zero. Individual forces can still do positive or negative work.

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