The foot
Second order lever in action.
By now it should be obvious that most of the levers found in the body are third order levers. Nature sacrifices mechanical advantage for an increase in distance traveled. Since the effort is placed so close to the fulcrum a great deal of force is needed to lift any significant load.
The foot however
is an example of a second order.
The foot is used to spring the body off the ground. Upon landing the
foot is gently placed on the ground by the contraction of muscles at
the front of the lower leg.
Look
at the animation above.
During stage "A" the foot springs the body off the ground.
What type of lever does the foot represent during stage "A"?
Does this lever give a mechanical advantage or is it a distance multiplier?
Explain.
Label the load, fulcrum and effort.
During stage "B" the foot lands on the ground.
What type of lever does the foot represent during stage "B"?
Does this lever give a mechanical advantage or is it a distance multiplier?
Explain.
The gastrocnemius is a very powerful muscle, one of the strongest muscles in the body. Why does this muscle need to be so powerful?
Look at the video(80Kb) of a person moving their foot. The foot rotates around the ankle. What type of lever is this? Draw the lever and label the fulcrum, load and effort.