Download Energy Notes - upsd.wednet.edu

Energy Notes
Energy



When you do work on an object you
must displace that object from its
rest position.
In this case that object then has the
ability to do work on some other
object (one way is for the original
object to collide into it)
We call this ability to do work
ENERGY.
Energy


Energy can exist because of the
object's motion (Kinetic Energy)
It can also exist because of its
position (Potential Energy).
Kinetic Energy




Kinetic Energy=.5 (mass)(velocity)2
KE= .5mv2
the units on this will be kg m2/s2 or a
Joule—J (Nm—newtons x meters)
Sample Problem p. 193
Potential Energy


There are different types of potential
energy (chemical, elastic,
gravitational, & nuclear), but all
depend upon the position of the
object.
Gravitational Potential Energy (GPE)
is the energy due to an object's
position above the Earth.
Gravitational Potential Energy



G.P.E. = (mass) x (acceleration of
gravity) x (displacement of the
object to the earth)=m•g•h
The units on this would also be a
Joule.
Sample Problem p. 191
Elastic Potential Energy



Elastic Potential energy is the energy due
to the stretching or compression of an
elastic material.
E. P. E. = .5 x (elasticity constant) x
(amount of displacement from
equilibrium)2= .5 k Δx2
The units for k (elasticity constant) are in
N/m
Non-mechanical Energy



If the energy is a macroscopic quantity it
is considered to be mechanical energy
(most kinetic or potential energy).
If not, then it is considered nonmechanical.
Heat, Sound, Light, and all other
electromagnetic radiation are types of
non-mechanical energy. (and actually are
kinetic)