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Work-Energy, Power, and Momentum
Check it out! Click on the Newton's Cradle above to learn about conservation of momentum!
Energy is anything that can be converted into work
(Anything that can exert a force through a distance)
Two Types of Energy:
 Potential Energy: Ability to do work by virtue of position or condition
Ep = mgh
 Kinetic Energy: ability to do work by virtue of motion
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Work: the product of the force exerted on an object and the distance over which the force is exerted
-Work is a scalar quantity (has magnitude but not direction).
Three Requirements to Perform Work
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An applied force F must act on the object.
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The force must be applied over a displacement.
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The force must be exerted at least in part along the displacement.
Although force is applied in both of these situations, no work is performed because the force isn't applied over a distance.
Resultant Work- equal to the sum of the work done by each force acting on the object
Work Energy Theorem
The work done by a resultant force is equal to the change in kinetic energy it produces.
Work = ½mvf2 – ½mvo2
A baseball pitcher does positive work on the ball by transferring energy into it.
Power is the ability to do work over a period of time.
Momentum: a measure of the motion of a body to the product of its mass and velocity
When two objects collide, they can exist as either elastic or inelastic collisions, where their momentums contribute to one another, changing their resultant velocities.
Elastic collisions: An elastic collision is an encounter between two bodies in which the total kinetic energy of the two bodies after the encounter is equal to their total kinetic energy before the encounter. Elastic collisions occur only if there is no net conversion of kinetic energy into other forms.
Inelastic collision: a collision in which kinetic energy is not conserved
A bouncing ball captured with a stroboscopic flash at 25 images per second. Each impact of the ball is inelastic, meaning that energy dissipates at each bounce.
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