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Section 3
What Is Energy?
But first, let’s review:
1. How do we define work?
Energy transferred by a _____ Force applied to a body Body moves in _______________
force
direction of force
2. How do we calculate work?
Work = ______x _________distanceforce
Unit for work ________.Joule (J)
But first, let’s review:
1. How do we define Power?
The rate at which _____ is done. work
2. How do we calculate power?
Power = timework
Unit for power_________.Watts (W)
I. Energy & Work
A. Energy – ability to do work.REMEMBER: work is applying a force to something in order to move it.
dd
work = force x distance
1. Energy – No change in position required. (no movement)
Both the wrecking ball & the bow possess STORED energy.
B. Energy must have the ability and/or cause a change in position.
1. In other words: energy can be transferred.
II. Potential EnergyA. Potential Energy – Stored Energy, sometimes
referred to as positional energy
Elastic Potential Energy
B. Gravitational Potential Energy – Depends on the mass & height of an object.
III. Kinetic EnergyA. Kinetic Energy – Energy of a moving
object.
Kinetic Energy = ½mass x velocity2
KE = ½mv2
Kinetic EnergyPotential Energy
GPE = mass x acceleration x height
Mass = kilogram (kg)
Acceleration = 9.8m/s2
Height = meters
KE = ½mass x velocity2
Mass = kilogram (kg)
Velocity = m/s
Pg. 395, questions 1 – 3 Pg. 393, questions 1 – 4