Paper 1 - Biomechanics Flashcards
Define force
A push or a pull that alters, or tends to alter, the state of motion of a body
Something is stationary when the net force is 0 (e.g. gravity one way, your hand the other way OR in space no forces)
Define velocity
Velocity - The rate of motion in a particular direction/the rate of change in displacement (speed is the rate of change in distance)
Define momentum
Momentum - The quantity of motion possessed by a moving body (momentum increases by speed or weight increasing)
Define acceleration
Acceleration - The rate of change of velocity
What are newtons 3 laws
1st : Law of inertia
2nd : Law of acceleration
3rd : Law of reaction
Newton’s 1st Law of motion (define & examples)
Newton’s 1st Law of Motion - The Law of Inertia
A body continues in a state of rest or in uniform velocity unless acted upon by an external force.
Inertia = laziness in Latin
Everything in the universe is lazy. Force is needed to get it to move, Force is needed to slow it down, stop it, speed it up, or change direction.
E.g. Stationary body will remain at rest until an external force is applied. (Centre pass in netball, ball remains in the player ( C ) hands until a force is applied to pass the ball).
E.g. Moving body will continue to move with constant velocity until made to change its speed and/or direction by an external force. (The ball will travel at constant velocity in the direction thrown until caught by another player).
Newton’s 2nd Law of motion (define & examples)
Newton’s 2nd Law of Motion - The Law of Acceleration
When a force acts on an object, the rate of change of momentum experienced by the object is proportional to the size of the force and takes place in the direction in which the force acts.
E.g. The greater the force applied, the greater the acceleration, the greater the momentum, the greater the distance travelled, (Netball shooter close to the ring will only need to impart a small amount of force towards the ring, however further away the shot will need greater force as it needs more momentum to travel to the goal)
Newton’s 3rd Law of motion (define & examples)
Newton’s 3rd Law of Motion - The Law of Reaction
For every force that is exerted by one body on another, there is an equal and opposite force exerted by the second body on the first. (For every action there is an equal and opposite reaction).
E.g. For every action there is an equal and opposite reactions (Netball bounce pass, the ball then travels down towards the floor, downward action force of the ground, that is turn exerts an upward force on the ball and the ball bounces up)
(Netball bounce pass, the player exerts an action force of the ball in the downward direction. The ball exerts a reaction force in the upward direction on the player, a slight increase in pressure in the fingers).
Define linear Motion
When a body moves in a straight or curved line (curved when a force acts upon it but its velocity is going in one straight direction), with all parts moving in the same direction at the same speed
E.g. tennis ball, satellite in space
Sporting Example : A performer in the skeleton bobsleigh will travel with linear Motion sliding down the straight parts of the track and with linear Motion in a curved line when sliding around the bends.
Angular motion = object has spin therefore is turning
What are the different types of force
Action
Reaction
Internal
External
Horizontal/vertical
Net
Define action force
Action force = A force exerted by a performer on another body (e.g. the backwards and downwards force entered by the sprinter on the blocks at the start of a race).
Define reaction force
Reaction force = An equal and opposite force to the action force exerted by a second body on the first (e.g. the forward and upward reaction force exerted by the blocks on the sprinter at the start of the race)
Define internal force
Internal force = Generated by the contraction of skeletal muscle (e.g. 100m contracts the leg muscle to generate the force required to drive away from the block)
Define external force
External force = Comes from outside the body and acts upon it. The force of weight, reaction, friction and air resistance
Define/explain net force
Net force = Is the sum of all forces accruing on a body (also called resultant force). It is the overall force acting on a body when all individual forces have been considered. (If a net force = 0, there is no change in motion as the forces are balanced). A body will remain at rest or continue to travel with constant velocity.
E.g. rugby scrum (both packs push forwards with equal force, net force = 0)
If a net force is present, there is a change in motion as the forces are unbalanced (a body either accelerates (+ net force), decelerates (- net force), change its direct or change of shape (e.g. + down force)
E.g. if a net force is positive a body will accelerate (when a netball makes a chest pass, the forward force applied is greater than the air resistance so therefore accelerates)
E.g. if a net force is negative a body will decelerate (when a shuttlecock is hit hard it will decelerate rapidly as air resistance acts in the opposite direction of motion)
