Biomechanics Flashcards
Scalar and Vector quantities
Scalar - Size
Vector - Size and direction
Mass definition
The quality of matter the body possesses
Weight definition
The gravitational force exerted on an object
Distance and Displacement
Distance - the path the body takes to move from start to finish
Displacement - shortest distance in a straight line from start to finish
Speed and Velocity
Speed = distance/time
Velocity = displacement/time
Acceleration definition and equation
The rate of change of velocity
Change in velocity/time
Momentum definition and equation
The product of the mass and velocity of an object
Mass x Velocity
Weight equation
Mass x acceleration
Difference between Vertical forces and Horizontal forces
Vertical forces - two bodies in contact with another, reaction force
Horizontal forces - two or more bodies are in contact with one another, frictional force (a force that acts in the opposite direction to the motion of a body travelling through the air)
3 factors affecting friction
- surface characteristics
- the temperature of the surfaces
- the mass of the object
What does a horizontal force depend on?
- the faster the velocity, more resistance
- the larger cross section, more air resistance
- the shape and surface characteristics
How do forces act on the body during linear motion?
Friction force : forwards ->
Air resistance : backwards <-
Weight : downwards
Reaction force : upwards
Net force
The resultant force after all other forces have been considered
Newtons 3 laws of motion
1st law : Object will not change its motion until a force acts upon it
2nd law : acceleration
3rd law : equal and opposite directions of forces
Impulse equation
Force x Time
Torque
The rotational consequence of force (where you put finger to open door)
Torque equation
Force x distance from fulcrum
3 quantities of angular motion and conservation of angular momentum
Angular velocity
Angular acceleration
Moment of inertia
Angular velocity
Rate of rotation of a body around its axes of rotation
Angular acceleration
Rate of change of angular velocity
Moment of inertia
Body’s reluctance to alter rate of rotation
What affects drag force?
- the shape
- the surface
- reducing cross sectional area
- streamline
The Bernoulli principle (discus example)
Where air molecules exert less pressure the faster they travel and more pressure the slower they travel
- Air tries move high to low pressure
- Angle of attack - if altered creates hydrofoil shape
- Air travels faster over top of discus
- Air travels further over the top of the discus
- This creates a low pressure on top of discus
- aerofoil shape
Mechanical advantage of third-class lever operating at hip for long jumper
- mechanical advantage is so large ranges of movement can be moved quickly
- 3rd class levers have a faster range of movement
- flexing at hip gain forwards movement + jump further
What is horizontal displacement?
Distance something has travelled
3 factors affecting horizontal displacement
- angle of release
- speed of release
- height of release
Parabolic curve definition
A curve with matching left and right sides
Factors affecting flight paths (2)
- gravity
- air resistance
1st law of newton
Inertia law
- moving constantly until force applied
- force applied by muscles
- performer continue in current state until another force applied
2nd law of newton
Law of acceleration
- force = mass x acceleration
- mass is constant
- to accelerate u need more force
- force produced by muscle contractions
- ground reaction force produced
- greater the force greater the acceleration
3rd law of motion
Law of action and reaction
- equal and opposite reaction
- athlete produce force into ground/onto object
- ground/object apply equal and opposite force back on athlete
Eg sprinter
Factors affecting stability
- height of centre of mass
- area of base of support
- position of line of gravity
- body mass
What is optimum angle of release?
45
