What is the equation for torque?
Torque = force x distance
What is the equation for mechanical advantage?
MA = effort arm / resistance arm
What is mechanical advantage?
- The ability to preform more work with less effort
- The ability to move more weight easier
- A numerical value used to describe the efficiency of simple machines
What is mechanical disadvantage?
- When the MA number is less than 1
- Means that there needs to be a lot of effort for the movement that won’t be strong, but can happen fast with lots of range of motion
What does it mean when the mechanical advantage ratio is greater than 1?
- The effort arm is larger than the resistance arm
- There is increased mechanical advantage (efficiency)
What does it mean when the mechanical advantage ratio is less than 1?
- The effort arm is smaller than the resistance arm
- There is no mechanical advantage (aka there is a mechanical DISadvantage)
- There can be greater displacement and speed of the load)
What range of mechanical advantage can a first class lever supply?
- 1st class levers can create both a mechanical advantage and a mechanical disadvantage
- The lever can favor either power OR distance depending where the fulcrum is placed (and how that affects the ratios of the arms)
What range of mechanical advantage can a second class lever supply?
- The mechanical advantage will always be higher than 1
- The force arm by definition will always be longer than the resistance arm
- This lever always favors strength
What range of mechanical advantage can a third class lever supply?
- There will always be a mechanical DISadvantage
- The force arm by definition will always be shorter than the resistance arm
- This lever always favors motion and speed
What type of lever is most common in the body? Why? What is bad about this?
- 3rd class levers
- They provide better motion
- It allows for muscles to be packed better
^ It means we need to work a lot harder to move things
What does it mean when the torque is 0?
There is no movement
How can you compare two efforts?
Force 1 x distance 1 = force 2 x distance 2
Why is it important to know that humans are mostly ___ class levers when working with patients?
We can manipulate the resistance arm and effort arm ratios to allow the patient to work harder (or not as hard) for certain movements