levers Flashcards
state one mechanical advantage of the 2nd class lever (1)
overcomes heavy loads/weight
(must refer to lifting)
large force is generated/longer effort am and reduced effort needed.
eg can move large(er) loads with relatively low effort compared to eg a 3rd class lever
how to calculate mechanical advantage (formula) and what does this measure
effort arm/load arm
measures the efficiency of a lever
1st class lever in the body (2)
extension at the elbow
f=elbow
e=tricep
l=thing in hand eg ball
neck for eg heddering the ball
what is a lever
a rigid bar that turns about an axis to create movement
where is the effort
the muscle INSERTION
which direction is the effort drawn
in the direction of the muscle contraction eg if knee extension, quads shorten so arrow upwards
which lever isnt as strong as the others, but what does it have
3rd class but it does allow speed and a good range of movement (which is to do with the position of the fulcrum relative to the effort)
benefits of longer load arm
the longer the greater the speed can be generated and the better the range of movement
1st class, ext elbow and 3rd class
however isnt great at lifting heavy loads
benefits of longer effort arm
the greater the strength generated by the lever and therefore less effort needs to be provided
how to make levers more effective and eg
use a racket, oar, bat, ski poles
rackets and clubs are extensions of 3rd class levers, increasing length of LA and so increasing speed at the end of it. longer arm in general = more speed
the photograph shows a long jumper about to take off from the board with their right leg
analyse how the msk and lever systems operate at the right knee and ankle to achieve effective take off (8)
AO1:
the ankle is a hinge joint which is made up of the talus, tibia and fibula.
the muscles working at the ankle are the gastrocnemius and tibialis anterior.
the knee joint is a hinge joint made up of the femur and tibia.
the muscles are the quadriceps and hamstrings.
levers are made up of a fulcrum, effort and a load
the photograph shows a long jumper about to take off from the board with their right leg
analyse how the msk and lever systems operate at the right knee and ankle to achieve effective take off (8)
AO2:
during the take off there is plantar flexion at the ankle occurring due to the concentric contraction of the gastrocnemius which is the agonist. antagonist is TA, sagittal plane, transverse axis.
knee extension, concentric contraction of quads, the agonist. the antagonist is hamstrings, sagittal plane, transverse axis.
during take off:
lever system at ankle is 2nd class
at knee is 3rd class
the photograph shows a long jumper about to take off from the board with their right leg
analyse how the msk and lever systems operate at the right knee and ankle to achieve effective take off (8)
AO3:
3rd class at knee is mechanical disadvantage/no mechanical advantage, EA shorter than LA, a larger range of movement, contraction of quads needs to be forceful to overcome this, allow jumper to apply good force and move mass quickly.
2nd class at ankle is mechanical advantage, EA longer than LA so aids long jumper to drive their mass off the board so less speed
if the long jumper sinks into the board, the right leg will flex more at the ankle and knee which will cause the quads and gastro to eccentrically contract under the load. they will then initiate/apply a concentric contraction of these muscles leading to a powerful explosion off the take off board
the ankle operates as a lever as an athlete pushes off the ground to clear a hurdle
identify the class of lever operating a the ankle and explain the mechanical advantage of the class of lever for the athlete (3)
second class lever system (1)
longer effort arm (1) therefore the hurdler provides minimal effort to generate height to clear the hurdle (1)
the photograph shows an athlete performing a long jump (jumping phase/pike)
a 3rd class lever is operating to allow flexion at the hip, explain the mechanical advantage of the 3rd class lever at the hip for this athlete (2)
mechanical advantage means large range of movement and the load can be moved quickly
by moving the legs forwards in front of them/flexing at the hip/lifting legs higher to allow them to jump further /so legs are thrown forwards quickly to gain forwards movement and jump further (1)
