Download Energy, Work, and Power

Energy,
Work, &
Power
Work (W)
The product of the force (F) applied to an
object over a distance (d) in which the object
travels as a result of the force
(Force and distance must be parallel to each other)
W  F d
Joule (j) is the base unit of work
1 joule  1newton 1meter
J  N m
Work Example
A student lifts a 22.5 Newton ball 1.22
meters in 5 seconds.
How many joules of work has the
student completed?
Solve for Work
W  F d
W  222.5N 1.22m
W  271J
Energy
Ability to do work
(light, heat, mechanical, chemical, electrical)
Roller coaster
NASA solar sail
Fuel cell
Forms of Energy
Potential Energy (Stored energy or gravitational energy)
The capacity to do work by virtue of position or
configuration
Forms of Energy
Kinetic Energy (Energy of motion)
Energy which a body possesses because
of its motion, which occurs anywhere from
an atomic level to that of a whole
organism
Energy Transformation
Chemical
Radiant
Electrical
Conservation of Energy
Energy cannot be created or destroyed, but it
can change from one form to another.
Energy Conversion
Changing one form of energy to another
Energy Conversion
Examples
Fossil fuels
Solar cells
Wind turbines
Hydroelectric
Nuclear
Chemical → Heat → Mechanical → Electrical
Sunlight → Electrical
Kinetic → Mechanical → Electrical
Gravitational potential → Mechanical → Electrical
Nuclear → Heat → Mechanical → Electrical
Vehicle System Conversion
Chemical
Mechanical
Heat
Which output is desired, mechanical or heat?
Power
Rate at which work is performed or
energy is expended
W
P=
t
Watt is the base unit of Power
One watt is equal to 1 joule of work
per second
Power Example
A student lifts a 22.5 Newton ball 1.22 meters
in 5 seconds.
How many watts of power are used to lift the
ball?
Power = Work / Time
Work = 271.45J
271.45 J
P 
5.00 s
J
P  54.3
s
J
1  1 Watt(W )
s
P  54.3 W