5. Biomechanical Principles And Levers Flashcards
What are Newtons 3 laws?
- The law of inertia
- The law of acceleration
- The law of action/reaction
Define ‘newtons first law of inertia’
A force is required to change the state of motion
Define inertia
The resistance an object has to a change in its state of motion
Key points of Newton’s first law
- if an object is at rest, it will remain still
- if an object is moving in one direction it will continue to do so at the same velocity until another force is exterted upon it.
- the bigger the mass, the larger the inertia of an object
Sporting example for Newton’s first law
In a penalty, the ball will remain on the spot (state of rest) unless it is kicked by the player (external force).
Define ‘newtons second law of acceleration’
The magnitude (size) and direction of the force determines the magnitude and direction of the acceleration.
Key points of Newton’s second law
- the rate of acceleration is directly proportional to the force causing the change
What is the equation in Newton’s second law
Force = mass x acceleration (F = ma)
Sporting example for Newton’s second law
The harder the ball is kicked, the further and faster it will go in the direction that the force has been applied in.
Define ‘newtons third law of motion’
For every action (force) there is an equal and opposite reaction (force)
Key points of Newton’s third law
- always occur in pairs
Define ‘ground reaction force’
The equal and opposite force exerted on a performer who applies a muscular force on the ground.
Sporting example for Newton’s third law
When a footballer jumps (action) to win a header, a force is exerted on the ground to gain height. At the same time, the ground exerts an upward force on the player.
Define ‘scalar quantity’
When measurements are described in terms of just their size or magnitude.
How do you calculate speed?
Distance (m) / time (s)
