Work & Power
How the world works....
Work or Not?
11-0
What is Energy?
• Energy - ability to cause change:
can change the speed, direction,
shape, or temperature of an objoct
Define / Describe
WORK
• Work is done when a force causes
an object to move in the direction
that the force is applied.
• The formula for work is: W = F X D
• It there is no movement, there is no
work
Joules?
Work is measured in Joules
Nior york
Work (Joules) - Force (Newtons) X
meters)|
Exampie to calculate Work
Question: A weightifter raises weights of 2000
weight of 2 meters.
How much work has been done
W - 2000 X 2
W = 4000 Joules
What is Power?
Power is the rate at which work is done.
Power is measured in Watts.
Power (Watts) = Work (Joules) / Time
P-W/?
Question: A weightifter ifted 2000 Newtons
ut is the power output li this was
done in 2 seconds?
two wings tast
happen for work to be
done.
• A force must applied to an
object
• The object must move in the
same direction as the force.
How do machines
make work easier?
Any change in the size of the force
changes the distance. No machine can
increase both force and distance.
1. Multiply force which decreases distance
the load moves.
2. Multiply the distance which decreases
3.
force.
Or, they leave force and distance alone
but change the direction in which the
load moves.
What is mechanical
advantage?
The number of times a machine
multiplios the effort force.
What is purpose of a machine?
• To make work easier.
How do machines
make work easier?
• They can change the amount of
force
• They can chango the distance
(Remember that Work » Force X
Distance)
• They can also change the direction
MORE -
What are the 3 types
of simple machines?
• There are three simple machines:
• the lever, the pulley, and the
inclined plane
The wheel and axle, the wedge,
and the screw are modifications of
the three simple machines.
What is a compound
(or complex) machine?
• A machine made up of
two or more simple
machines.