P1 23. Levers Flashcards
what’s a lever
a rigid structure such as a bone that rotates around an axis
what is a fulcrum (pivot)
the point around which the lever rotates (your joint)
what is a load
the force applied by the lever system (the thing you want to move such as a weight, an arm or a leg)
what is an effort
the force applied by the user of the lever system (effort supplied by your muscles)
what are the three types of lever
first class
second class
third class
what is a first class lever
when the fulcrum is in the middle
load, fulcrum, effort
when an athlete throws a javelin
elbow is fulcrum
effort is biceps and triceps (contracted to keep arm straight)
javelin is load
what is a second class lever
load in the middle
fulcrum, load, effort
a calf raise
body weight is the LOAD sitting between the balls of the foot (FULCRUM) and the calf muscle applies EFFORT to life the heel off the floor
wheelbarrow raise position too
what is a third class lever
effort in the middle
load, effort, fulcrum
occur when the effort is applied between the fulcrum and the load
a bicep curl
fulcrum is elbow
load is weight
effort is bicep pulling up
how do you remember the different lever’s positioning
123FLE
F1L2E3
what are 2 benefits of levers
large loads can be moved with a relatively small amount of effort
the distance the load can be moved or the speed with which it can be moved can be increased without an increase in effort
what is a mechanical advantage
a large load can be moved with a relatively small effort
what is a mechanical disadvantage
third class levers cannot lift as heavy load with the same amount of effort, due to the position of the effort and load from the fulcrum
what is the effort arm
the distance between the fulcrum and the effort
what is the load arm
the distance between the load and the fulcrum
mechanical advantage
levers can move large loads with a relatively small amount of effort
have a high force to effort ratio
second class levers always have mechanical advantage
long jump take off
foot is in contact with the ground, effort is longer than load
the force produced is relatively small so full weight can be driven off the ground
mechanical disadvantage
low load force to effort ratio
third class levers always have mechanical disadvantage
when bowling in cricket the arm is fully extended to generate the most speed
longer load arm, greater the speed
what is the hip
third class
can’t produce the same load force to effort ratio as a second class lever
third class levers can take a small movement near the fulcrum and make a large movement where the load is
what is it where the load arm is longer than the effort arm
mechanical disadvantage
third class
bicep curl
what is it where the effort arm is longer than the load arm
mechanical advantage
first/second class
calf raise
what happens if the fulcrum is closer to the load in a first class lever
relatively low effort will result in large more powerful movements at the load end, mechanical advantage
what happens if the fulcrum is closer to the effort in a first class lever
lever will operate at mechanical disadvantage but will produce a large range of movement at the end of the lever and greater speed as a result
why is a second class lever always a mechanical advantage
when a levers effort arm is longer than the load arm
move a large load will small effort
high load to force ratio
why is a third class lever always a mechanical disadvantage
load arm is longer than the effort arm
low force to effort ratio
increase distance covered and speed
large range of movement with low effort
small movement near fulcrum and make large load actions which leads to large movement range and high speed
a rounders bat hit
