Transcript Levers - Haiku

Levers
effort
resistance
A lever consists of a rod or bar
that rests and turns on a support
called a fulcrum.
A force of effort is applied at one
end of the rod to lift a load placed
at the other end. A lever can help
lift a weight with less effort.
effort
resistance
fulcrum
Prying something loose with a
crowbar is using a lever. Some
machines, such as a catapult,
use a lever to hurl objects.
Here is a catapult you could make.
Three Classes of Levers
• First Class Lever
– The fulcrum is between the effort force and
the resistance force.
effort
resistance
fulcrum
Three Classes of Levers
• Second Class Lever
– The resistance is between the effort and the
fulcrum.
Three Classes of Levers
• Third Class of Lever
– The effort is between the fulcrum and the
resistance.
First Class Lever
Second Class Lever
Third Class Lever
Levers in the Body
How bones and muscles work
together!
Work is the
ability to apply a force that moves a body in
the direction of that force.
Levers makes work easier by changing:
•the amount of force.
•the distance over which the force is exerted.
•the direction of the force.
1st Class Lever
• An example of a first-class lever is the joint between the
skull and the atlas vertebrae of the spine: the spine is
the fulcrum across which muscles lift the head.
2nd Class Lever
An example in the human body of a second-class
lever is the Achilles tendon, pushing or pulling
across the heel of the foot.
3rd Class Lever
An example of a third-class lever in the human
body is the elbow joint: when lifting a book, the
elbow joint is the fulcrum across which the biceps
muscle performs the work.
What types of levers are all of
these?
Third Class Levers
Mechanical advantage is the number of times a
lever increases a force exerted on it.
Let’s Practice
•
•
•
•
Name the type of Lever
Point to the Fulcrum
Point to the Effort
Point to the Load
First Class Lever
Effort
Load
Fulcrum
Third Class Lever
Effort
Load
Fulcrum
Second Class Lever
Effort
Load
Fulcrum
Third Class Lever
Effort
Load
Fulcrum
First Class Lever
Effort
Fulcrum
Load
Third Class Lever
Effort
Load
Fulcrum
The End