Transcript Slide 1

Forms of Energy
Types of Energy
Renewable and
Nonrenewable Sources
Law of Conservation
of Energy
Work
Radiant
Thermal
Electrical
Nuclear
Chemical
Sound
Mechanical
Magnetic
Renewable
Nonrenewable
Kinetic Energy
Potential Energy
Potential energy + Kinetic energy =
Mechanical energy
Example of
energy changes
in a swing or
pendulum.
The greater the mass or velocity of a moving object, the
more kinetic energy it has.
Kinetic energy exists whenever an object which has mass
is in motion with some velocity. Everything you see
moving about has kinetic energy. The kinetic energy of an
object in this case is given by the relation:
KE = (1/2)mv2
m=mass of the object
V=velocity of the object
The greater the mass or velocity of a moving object, the
more kinetic energy it has.
Potential energy exists whenever an object which has mass
has a position within a force field. The most everyday
example of this is the position of objects in the earth's
gravitational field. The potential energy of an object in this
case is given by the relation:
PE = mgh
PE = Energy (in Joules)
m = mass (in kilograms)
g = gravitational acceleration of the earth (9.8 m/sec2)
h = height above earth's surface (in meters)
Law of Conservation of Energy- Energy can
neither be created nor destroyed. Energy is always
changing from one kind to another. The total
energy of an object never changes.
Potential energy + Kinetic energy = Total energy
and
Total energy – Kinetic energy = Potential energy
and
Total energy - Potential energy = Kinetic energy
Work is the transfer of energy through motion. In
order for work to take place, a force must be exerted
through a distance. The amount of work done
depends on two things: the amount of force exerted
and the distance over which the force is applied.
There are two factors to keep in mind when
deciding when work is being done: something has to
move and the motion must be in the direction of the
applied force. Work can be calculated by using the
following formula:
Work = force x distance
Work = DKE
Check Your Understanding
A = 50 J
D = 50 J
G = 100 J
J = 100
B = 7m/s
E = 7 m/s
H = 10 m/s
K = 10 m/s
C = 50 J
F=0J
I=0J
Check Your Understanding
• 1) How much work is required to lift a 162
kilogram piano to a window whose height
is 4.5 meters from the ground?
W = F x distance
F = 162Kg x 9.8m/s2 = 1590 N
W = 1590 N x 4.5 m = 7200 Nm