Biomechanics Levers Flashcards
- What rhyme should you sing when asked to identify what type of Lever is being used.
- Also, name the three parts of a lever
Remember the Insertion point on the bone dictates where the effort arm is!
1, 2, 3 Think F, L, E
The part that is in the middle identifies the type of lever, e.g if the Effort is in the middle it is a third class lever.
Third class lever
Fulcrum is the elbow joint
Load is the racquet
Effort is the tricep and bicep which attaches to the ulna bone, below the elbow joint
1,2,3 think FLE
What shapes represent the different parts of a lever?
Fulcrum= Triangle
Effort= Arrow (facing the direction of movement)
Load= Square
How do you draw a 1st class, 2nd class and 3rd class lever?
*You organise the parts of the lever as they’re shown in the image.
* The direction of the Effort arrow changes depening on the direction of movement
For example, the upward phase of a Bicep curl is a third class lever. The Load is the dumbbell which is on the right, the Effort is the bicep in the middle and the Fulcrum is the elbow on the left.
What is the formula for calculating mechanical advantage?
Effort arm divided by weight (resistance) arm
What are the characteristics of a 1st and 3rd class levers in relation to mechanical advantage?
Mechanical advantage- 1st and 3rd class levers facilitate a large range of movement and can move loads quickly.
Mechanical disadvantage- cannot apply much force.
1st class lever have a neutral mechanical advantage
3rd class levers have a low level of mechanical advantage
What are the characteristics of a 2nd class lever in relation to mechanical advantage?
Mechanical advantage- 2nd class levers can produce high levels of force.
**Mechanical disadvantage- **has a limited range of movement and moves slowly.
2nd class levers have a high level of mechanical advantage
A sprinter is driving out of the blocks in a 100 m race.
Analyse how the lever systems operating at the ankleandknee give the sprinter an effective start.
Include fully labelled diagrams of the lever systems in your answer.
[total 8 marks]
AO1: Knowledge of lever systems(can be credited in diagrams)
* Lever systems are made up of three components: the effort, fulcrum, and resistance.
* In linear diagrams the effort is represented as an arrow, the fulcrum by a triangle, and the resistance as a square/arrow.
* 2nd class – resistance in middle/3rd class effort in middle.
* Mechanical advantage is calculated as effort arm divided by resistance arm.
AO2: Application to 100 m start
* Ankle is a second-class lever system.
* Knee is a third-class lever system.
AO3: Analysis of how the lever systems operating at the ankle and knee allow an effective start in the 100 m
* The second-class lever system at the ankle has a high mechanical advantage as the effort arm is longer than the resistance arm.
* This allows the lever system to produce more force relative to the effort produced by the gastrocnemius muscle.
* This allows the sprinter to drive out of the blocks with greater force/overcome inertia more easily/accelerate faster.
* The third-class lever system at the knee has a low mechanical advantage/mechanical disadvantage as the effort arm is shorter than the resistance arm.
* While this means the knee requires more effort to overcome the resistance it does, however, mean that the lever system can move quickly and over a large range of motion.
* This allows the sprinter to cover a larger distance quickly as they drive out of the blocks using their large quadricep muscles to apply the necessary force.
* The two lever systems combine/complement each other to produce powerful start with high force and speed.
Accept any other appropriate analysis of how the lever systems operating at the ankleandknee give the sprinter an effective start with fully labelled diagrams of the lever systems included in the answer.
Which lever system is operating at the elbow as the javelin is released during the execution of the throw?
First class lever
The image below shows the movements involved as a player throws the ball on to the field of play during a game of rugby.
Using the figure, name, sketch and label the lever system operating at the elbow during the movement from PositionAto PositionB.
Name of lever system:
(Total 3 marks)
First class / order
Correct order – Fulcrum in middleCorrect labels – resistance / fulcrum / effort.
Other way around is still correct.
Stateonemechanical advantage andonemechanical disadvantage of the lever system that is being used at the right ankle as the runner in the figure above moves from PositionAto PositionB.
Mechanical advantage
Mechanical disadvantage
(Total 2 marks)
Must be identified as advantage or disadvantage
Advantages
Larger forces generated / longer force / effort arm
Easy to move heavy / large weight
Sub max 1 mark
Disadvantages
Limited range of movement
Limited / reduced speed of movement
Sub max 1 mark
Name, sketch and label the lever system that is operating at the elbow during the movement fromAtoB.
Lever system:
(Total 3 marks)
3 marks for 3 of:
First class / order / lever / system;Correctly labelled – fulcrum / pivot; effort / force; load / resistance / weight;Correct order – Fulcrum / pivot in middle
Typically what class of lever operates at the:
- Elbow and Neck
- Ankle
- Everything else
Elbow and Neck=1st class levers
Ankle= 2nd class lever
Everything else= 3rd class lever
