Biomechanics (needs splitting)

Newton's First Law

A body will remain in a state of rest or uniform motion until it is acted on by another force

Which law is the Law of inertia?

Newton's first law

Newton's Second Law

Acceleration is directly proportional to the magnitude of the applied force

Equation for Newton's second law

Force = mass x acceleration

Newton's Third Law

For every action there is an equal and opposite reaction

Centre of mass

Point of balance or concentration of mass

Factors affecting stability

Height of centre of mass, Area of support base, Mass of performer

How the height of the centre of mass affects stability

Lower height = Increased stability

How the area of support base affects stability

Larger base = increased stability

How does body mass affect stability

Greater mass = more stable

Scalar quantity definitions, equations and units

Distance - Total length of the path travelled from start to finish, measured in metres. Speed - Rate of change of distance, measures in m/s. Mass - amount of matter contained within a body, F=MA, measured in KG

Vector quantities examples (Diddy Vikstar Ate With Me)

Displacement - Shortest straight line route from start to finish metres. Velocity - Speed of a body in a specific direction, displacement/time, m/s. Acceleration - How quickly the velocity of a body is changing, F=MA, m/s2. Weight - Force of gravity acting upon mass off a body, W=MA, Newtons. Momentum - how difficult it is to stop a moving object, Momentum = MV, kg m/s

Lever

Turns around an axis to create movement

Fulcrum

Fixed point or joint where the lever pivots

Load

The weight that needs moving

Effort

Force applied to the load

1st class lever movement

Extension at the elbow

2nd class lever movement

Plantar flexion

3rd class lever movement

Human movement predominantly this

Mechanical advantage

Effort arm > Resistance arm which means a small effort overcomes large loads

Mechanical disadvantage

Resistance arm > Effort arm allows greater speeds and distances of movement

Linear motion

Movement in a straight line.

Scalar quantity

Size or magnitude

Vector quantity

Size and magnitude

Factors acting during linear motion

Weight, Friction, Air resistance, Gravity, inter-muscular force

Impulse definition and relationship with momentumn

Impulse is the product of force and time which is equal to change in momentum. Positive net impulses cause acceleration through applied force, negative net impulses cause braking by placing foot in front of the centre of mass.

Angular motion

Movement of a body around an axis of rotation

Torque (Newtons third law)

Rotational force causing an object to rotate. An off centre eccentric force is met by an equal and opposite reaction

Angular displacement

Change in angle between start and finish of rotation. Radians

Angular velocity

Rate of change of angular displacement. rad/s or m/s

Angular acceleration (Newtons second law)

Rate of change of angular motion and it is proportional to the torque applied. rad/s2

Angular momentum (Newtons first law)

Quantity of rotation a body possess which is constant in flight until acted on by external torque (Moment of Inertia x Angular velocity)

What determines the amount of angular momentum

If the moment of inertia changes the angular velocity must also change to keep momentum constant which is an inverse relationship

Moment of inertia

Resistance of a body to change its angular motion

Projectile motion

An object launched into the air

Horizontal displacement

The shortest distance from the starting point to the finishing point

Factors affecting horizontal displacement

Speed of release, Height of release Angle of release, Air resistance

Release height > Landing height

Landing height > release height

>45

Air resistance

Force opposing motion of a projectile

Factors causing air resitance

Low mass and Large surface area

Parabolic flight with example

A symmetrical flight path. Shot put has high mass and are smooth so gravity is dominant force over air resistance

Non parabolic flight path with example

Travels further on the way up then drops steeply. Shuttlecocks have low mass and large/rough surface area so air resistance significantly opposes motion

Vector components of parabolic flight

Vertical component - Gravity (weight) acts as external force to determine height of flight. Horizontal component - Air resistance is considering negligible which determines horizontal displacement. Resultant vector - combination between horizontal and vertical components

Fluid mechanics

The study of forces acting on an object through air/water

Factors affecting drag

Streamlining, Smoothness, Velocity, Surface area

Streamlining

Laminar flow occurs when air particles pass smoothly mover and behind an object (e.g cyclists teardrop helmets). If object not tapered at the back is causes turbulent flow that slows athlete down

Drag

Resistance opposing motion in fluids

Surface drag

Friction between an object and fluid moving over it, rough surfaces increase this

Form drag

An object moving through a fluid, increases with surface area

Bernoulli's Principle

As the speed of a fluid increases, its pressure decreases.

Aerofoil

Curved upper and flat lower surface generating lift

Air flow over the top of an aerofoil

Greater distance to travel means greater velocity and lower pressure

Air flow underneath an aerofoil

Less distance to travel so decreased velocity and greater pressure

What causes the lift force in Bernoulli's principle

Pressure gradient

Examples of aerofoils

Discuss , Javelin , Ski jumper

Examples of inverted aerofoils

F1 car, Track cyclist

Mechanical efficiency

How effectively a system converts the input energy or work into useful output energy or work