# A Level PE - Biomechanical principles and Stability

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• Created by: hotzmc
• Created on: 24-12-17 12:31

A Level PE - Biomechanic Principles & Stability:

Newton’s Law’s of Motion:

1. A body continues in a state of rest or uniform velocity unless acted upon by an external or unbalanced force
2. A body’s rate of change in momentum is proportional to the size of the force applied and acts in the same direction as the force applied
3. For every action force applied to a body, there is an equal and opposite reaction force
• Understanding Newton’s laws of motion is important so that we can apply these laws during training to help improve performance

Newton’s First Law of Motion:

1. A body continues in a state of rest or uniform velocity unless acted upon by an external or unbalanced force
• The law states that in order to change somethings state of motion (in this case it is still), the resistance acting on it must have a greater force
• The greater the mass the greater the inertia - the resistance of a body to change its state in motion
• So if a 100m sprinter doesn’t put enough force into the starting blocks at the start of the race, they will not move

Inertia: The resistance of a body to change its state of motion, whether at rest or while moving

Newton’s Second Law of Motion:

1. A body’s rate of change in momentum is proportional to the size of the force applied and acts in the same direction as the force applied
• We understand that the greater the mass of a body, the greater the force needed to overcome the down gravitational pull and create motion
• The quantity of motion is called momentum, and it closely links to acceleration
• The rate of change in momentum & acceleration is proportional to the size of the force applied
• E.g. a 100m sprinter will want to generate as much forward force as possible to accelerate away from the blocks as fast as possible

Newton’s Third Law of Motion:

1. For every action force applied to a body, there is an equal and opposite reaction force
• An action force is generated and applied by the athlete to the ground or an object
• A reaction force is the equal & opposite force generated by the ground/object back to the athlete
• It’s this force that will, for example, tell an athlete whether the pass they made was successful or not before they see the outcome
• E.g. When an 100m runner applies a down & back action force into the blocks, the blocks provide an equal & opposite up & forward reaction to the