PE: levers
What are levers
Axis/Fulcrum
The pivot point
Resistance or load
The weight that needs to be moved
Effort
the force that is applied to move the resistance (or load)
Functions of a lever .
Function 1: To increase the resistance (or force) that can be moved with
a given effort e.g. a crowbar.
Function 2: To increase the velocity at which an object will move with a given force. E.g. A golf club.
First Class Levers
the fulcrum/axis lies between the Load and effort
example see saw
LFE
Force axis ressitance (FAR)
Second class lever
the load lies between the fulcrum and point of effort
example calf muscle
FLE
a real fight (ARF)
3rd class lever
effort lies between the load and fulcrum
example bat, arm, bicep curl
FEL
A foot race (AFR =Speed)
chracteristic
1st class chracteristic If force arm is longer advantage occurs if force arm is shorter better speed and range of movement
2nd class chracteristic less force can move the load
3rd class chracteristic Benefit greater speed and range of motion can be achieved
mechnical advantage
Mechanical advantage= force arm
resistance arm
When the force arm is longer than the resistance arm there is mechanical advantage (the calculation value above 1). This means that the force required to move the load is less than the force of resistance.
When the resistance arm is greater than the force arm there is no mechanical advantage calculation will show a value under 1 These leavers require a greater force, but have a larger range of movement and increase angular speed