Download Levers Information

Levers Information
Class 1 lever
This class has the fulcrum between the effort and the load.
Class 2 levers
These levers have the load between the fulcrum and the effort.
Class 3 levers
Class 3 levers have the effort between the fulcrum and the load.
Mechanical Advantage
When engineers design machines they need some way of predicting how the
machines will work. One way is to compare the size of the effort and the load and
you can use very simple mathematics to do this. When you compare the size of
the effort and the load it is called the mechanical advantage.
The lever is used to explain the idea of mechanical advantage.
Mechanical advantage
We use machines to allow us to change a small force at the effort into a larger
force to move the load. When we compare the sizes of the effort and the load we
are talking about the mechanical advantage.
We use the abbreviation MA for mechanical advantage and some very simple
mathematics to help us find the MA.
MA = Load ÷ Effort
If the machine uses a small effort to move a much larger load it is said to have a
good mechanical advantage.
Example
An effort of 10N is used to move a load of 50N. What is the MA of this lever?
MA = Load ÷ Effort
= 50 ÷ 10
=5
The mechanical advantage of the lever is 5. This means that whatever the size of
the effort you use it will move a load 5 times larger.
There are no units for mechanical advantage; it is just a number.
Velocity Ratio
When engineers design machines they need some way of predicting how the
machines will work. They can use very simple mathematics to help them design
the best machine. One way is to use what is called the velocity ratio.
The lever is used to explain the idea of velocity ratio.
Velocity ratio
You need to understand velocity and distance before you can understand the
idea of velocity ratio. A ratio is when we compare two similar things. To find the
velocity ratio we compare the distances the effort and load move in the same
time.
We use the abbreviation VR for velocity ratio and simple mathematics will give us
the answer.
VR = Distance effort moves ÷ Distance load moves
Example
If the effort moves 5 metres while the load moves 1 metre, what is the velocity
ratio?
VR
= Distance effort moves ÷ Distance load moves
=5÷1
=5
The velocity ratio of the lever is 5. This means that whatever distance the load
moves the effort must moves 5 times that distance.
There are no units for velocity ratio it is just a number.
Velocity
While speed of a moving body is important in technology there is another word
that is even more important and it is velocity.
To describe velocity you have to give the speed and the direction in which the
body is moving.