Unit 3 Biomechanics Flashcards
Newton’s first law
Body will continue in state of rest or constant velocity unless a resultant for a acts upon it
Newton’s second law
The rate of change of momentum is proportional to the size and direction of the resultant force
Newton’s third law
Every action has an equal and opposite reaction
Balanced forces
Equal in size but opposite in direction
Unbalanced forces
Unequal in size and opposite in direction
Weight
The gravitational pull that the earth exerts on a body
Reaction
An equal and opposite force exerted on a body in response to the action created by it
Friction
The force that opposes the motion of two surfaces in contact
Air resistance
The force opposes the motion as a body travels through the air
Free body diagram
Centre of Mass
(Weight) Downward
(Air resistance) Backward
Point of contact on ground
(Friction) Forward
(Reaction) Upward
Factors affecting friction
Temperature -> warming up tyres increases friction.
Surface characteristics -> rough or smooth (wearing studs)
Centre of mass
The point at which the body is balanced in all directions
Factors affecting position of the centre of mass
Distribution of body mass
Shape of the body
Factors affecting stability
Height of Centre of Mass
-> lower = better
Mass of body
-> larger = better
Line of gravity
-> above base of support = better
Points of contact
-> more = better
Base of support
-> large = better
Factors affecting air resistance
Surface characteristics
-> smooth
Size of surface area
-> small
Shape of body
-> aerofoil
Velocity
-> (fast=drag)
Calculations
Velocity
Displacement/time
Acceleration
(Velocity1-Velocity2)/time
Momentum
Mass x Velocity
Force
Mass x Acceleration
Weight
Mass x gravity
Lever system (LOAD)
Weight
Lever system (EFFORT)
Force applied by our muscle to move the lever
Lever system (FULCRUM)
Pivot point (joint)
Lever system (LEVER)
The bone
Lever system (EFFORT ARM)
Distance between effort and fulcrum
Lever system (LOAD ARM)
Distance between load and fulcrum
1st class lever system
(Seesaw)
la ea
______________________lever
| /\ |
L F E
- Heading the ball (Neck)
- Overarm throw (Shoulder)
2nd class lever system
(Wheelbarrow)
ea E
|
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_lever
/\|
F la L
-Sprint start (plantar flexion)
3rd class lever system
ea E
|
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_lever
/\|
F la L
-Bicep curl (flexion at the elbow)
Limb kinematics
Use of 3D/optical motion analysis to study movement in relation to time and space.
- > improve technique
- > specific limb/joint movement
- > measure velocity and acceleration
(golfing/sprinting technique)
Force plates
A plate used to measure ground reaction forces.
- > analyse the amount of force you can generate
- > can be used for injury rehabilitation
- > analyse running posture
(rugby/sprinting technique/high jump)
Wind tunnels
A chamber that measures air resistance acting on an object.
- > Improve air flow around an object
- > Create less drag to increase velocity
(track cycling/Formula 1)
Advantages and disadvantages (2nd class lever systems)
Advantages:
- Requires less effort to move an equivalent load.
- Effort arm is larger than load arm.
Disadvantages:
- Moves a smaller distance.
- Lower velocity/acceleration.
Advantages and disadvantages (3rd class lever systems)
Advantages:
- Moves a larger distance.
- Larger velocity/acceleration.
Disadvantages:
- Requires more effort to move an equivalent load.
- Load arm is larger than effort arm.
