Biomechanics

PE Biomechanics definitions and formulas

Force

Is defined as a push or a pull

Force formula

mass x acceleration

Inertia

The tendency for a body to resist a change in it’s state of motion

Momentum

A measure of the amount of motion an object has and it’s resistance to change that motion

Momentum formula

mass x velocity

Conservation of momentum

the total momentum of the system before the collision is equal to the total momentum after the collision

summation of momentum

the correct timing and sequencing of body parts to produce maximal force

impulse

is equal to the change in momentum of an object

impulse formula

force x time

newton’s first law

law of inertia, a body will remain at rest or in uniform motion in a straight line unless acted upon an outside force

newton’s second law

law of acceleration, a force applied to an object will produce a change in motion in the direction of the applied force that is directly proportional to the size of the force

newton’s third law

law of action/reaction, for every action, there is an equal and opposite reaction

torque

the turning effect caused by applying an eccentric force

torque formula

force x lever arm

angular momentum

the amount of angular motion possessed by a body

conservation of angular momentum

angular momentum is conserved when the body is in flight

linear motion

the movement of a body along a straight or curved path

angular motion

movement around a central axis

distance

measures the path travelled from start to finish

displacement

the change in position of an object

speed 

the ratio of distance covered to the time taken

speed formula

distance/time

velocity

the ratio of displacement to the time taken

velocity formula

displacement/time

acceleration

a change in velocity in a given period of time

acceleration formula

change in velocity/change in time

angular velocity

rate of change of angular displacement

projectile motion

object that moves along a curved path, as soon as the object is released into the air it is affected by gravity and air resistance.

factors affecting path of a projectile

angle or release, speed of release, height of release

angle of release

angle at which an object is projected into the air

speed of release

speed at which object is thrown, kicked or otherwise propelled into the air

height of release

difference between the height that a projectile is released from and the height at which it lands

equilibrium

when all forces and torques are balanced

balance

the ability to control the body’s equilibrium

levers

rotate around an axis to exert a force

third class levers

force is between the resistance and the axis (force is bicep muscle, resistance is in the hand, axis is elbow)

mechanical advantage

force arm/resistance arm (3rd class <1)