Year 12 PE: Chapter 2 Biomechanics ALL

Force

A 'push or pull' - causing a change in state of a body/object

Gravitational Force

This is the force exerted on the body/object due to gravity

Friction

This occurs when two surfaces come into contact with one another

Drag

An object that is moving through air or through water will experience a drag force, opposing the motion

Mass

The quantity of matter found in a body or object, typically measured in kilograms (kg)

Inertia

The reluctance of a body to change its state of motion either at rest or moving.

Momentum

Quantity /how much motion an object or body has

= Mass (m) x Velocity (v)

Impulse

Calculated as Force x Time

Conservation of Momentum

The conserving of momentum in a collsion

Summation of Momentum

Where body parts move in a sequence in order to maximise momentum

Force is first generated by the body parts with greater mass/inertia and then passed on to the smaller body parts - this allows maximum velocity

Newtons 1st Law of Motion

Law of Inertia

An object will stay at rest or continue to travel in the SAME direction at a constant velocity unless acted on by an external, unbalanced force

Newtons 2nd Law of Motion

The rate of acceleration of a body is proportional to the force applied to it and in the direction in which the force is applied

F= m x a

Newtons 3rd Law of Motion

For every action there is an equal and opposite reaction

When one body / object applies a force against a second body/ object then the second will apply an EQUAL force is the OPPOSITE DIRECTION as the first

Angular Motion

Body moves along a circular path - occurring around some type of axis (either internal or external)

Linear Motion

Is an object/body's change in position in relation to time in a straight line (rectilinear) or curved (curvilinear) path

Newtons 1st Law of Angular Motion

The angular momentum of a body remains constant unless acted upon by an external TORQUE

Newtons 2nd Law of Angular Motion

A torque applied to an object will produce an change in angular motion in the direction of the applied torque that is directly proportional to the size of the torque and the inversely proportional to the moment of inertia of the object

Newtons 3rd Law of Angular Motion

For every torque there is an equal and opposite toque

Torque

A force that causes an object/body to rotate around its axis

Angular Momentum

Angular momentum is how much angular motion (motion of a mass while it rotates) an object or body has.

= angular velocity x moment of inertia

Moment of Inertia

Moment of inertia is a tendency for a body/object to resist changes in rotary motion (rotation)

= mass x radius2 (radius of rotation)

Linear Motion - Distance

Distance measures a path travelled from start to finish, regardless of direction.

Linear Motion - Displacement

Displacement is defined as a change of position- how far it is from the initial position to the final position

Angular Distance

How many degrees an object moves around an axis

Angular Displacement

The difference between the initial and final angular position of an object-

Angular Speed

The angular distance covered divided by the

time taken to complete the motion

Angular Velocity

The rate of change of the angular displacement of a body over time

Angular Acceleration

The rate of change of angular velocity, or how quickly a body changes its angular position (measured in degrees per second squared)

Factors Affecting Projectile Motion

Velocity - higher velocity = greater air resistance

Mass - lower mass = greater air resistance

Shape- more streamlined = less air resistance, allowing air to flow over with less drag

Surface area - greater surface area = greater air resistance, as more surface is exposed to the air (ie: a badminton shuttlecock)

Nature of the surface area - smoother will decrease drag and = less air resistance

Factors affecting the path of the projectile

Angle of release of the projectile

Height of release of the projectile

Speed of release of the projectile

Lever

Has three parts::

- An axis (or fulcrum or pivot point

- A resistance (or weight or load to be moved

- A force (or effort)

First Class lever

Resistance and force are on either side of the axis. Set up like a see-saw

Second Class Lever

Resistance is between the force and axis

Found in the calf muscle.

Mechanical Advantage of Anatomical Levers

Mechanical advantage = Force arm/resistance arm

The force arm is the distance between the axis and the force and the resistance arm is the distance between the axis and the resistance.

When the resistance arm is greater than the force arm, there is no mechanical advantage- the ratio is less than one- but the range of motion of the lever is increased.

Third Class Lever

Force is between the resistance and the axis

The most common type of lever both in the human body and in sporting examples of human movement.

They require greater force to move a given resistance, but greater range of motion and speed are gained.

Equilibrium

there are no unbalanced torques or forces acting on a body and therefore are without motion or moving at constant velocity.

Stability

is the resistance to a disruption to equilibrium. Increase the stability, and it is more difficult to unbalance an objectDecrease the stability, and it is easier to unbalance an object

Balance

is the ability to control the state of equilibrium - either when stationary or whilst moving

Base of Support (BOS)

This is the area bound by the outside edges of the body parts in contact with the support surface

Centre of Gravity (COG)

A body or object's COG is the point around which weight is balanced/evenly distributed regardless of the position of the body

Line of Gravity (LOG)

An imaginary line passing through the COG showing the direction that gravity is acting on the object/ body