5.1: Biomechanical Principles And Levers Flashcards
1
Q
What is linear motion?
A
- motion in a straight or curved line, with all body parts moving the same direction at the same speed in the same direction.
- e.g. a 100m sprinter.
2
Q
What is Newton’s first law of motion?
A
- law of inertia
- a force is required to change the state of motion. If a body changes its state of motion, it starts, stops, accelerates, decelerates or changes direction.
- e.g. in high jump the athlete runs horizontally towards the bar and then changes their state of motion at take-off when they travel vertically to try to clear the bar.
3
Q
Inertia definition:
A
- the resistance an object has to a change in its state of motion.
- the bigger the mass, the larger the inertia of a body or object. This means tang more force will be needed to change its state of motion.
4
Q
Newton’s first law quote:
A
- ‘every body continues in its state of rest or motion in a straight line, unless compelled to change that state by external forces exerted upon it’.
5
Q
What is Newton’s second law of nature?
A
- the law of acceleration
- the magnitude (size) and direction of the force applied to a body determine the magnitude and direction of the acceleration given to a body.
- the rate of acceleration is directly proportional to the force causing the change.
- Force = mass x acceleration (F=ma).
- is the mass remained constant, then acceleration is equal to the size of the force causing it.
6
Q
Newton’s second law - example:
A
- tennis player will impart a large force on the ball so that accelerates over the net in the direction in which the force has been applied.
7
Q
Newton’s second law quote:
A
- ‘the rate or momentum of a body (or the acceleration for a body of constant mass) is proportional to the force causing it and the change that takes place in the direction in which the force acts)
8
Q
What is Newton’s third law of motion?
A
- for every action (force) there is an equal and opposite reaction (force)
- e,g. the athlete pushes back on rue blocks as hard as possible and the block pushes forward on the athlete and provides forward acceleration on the athlete.
9
Q
What is ground reaction force (GRF)?
A
- the force exerted on the ground by the body in contact with it.
- an individual standing still on the ground exerts a contact force (individual’s weight) and at the same time, an equal and opposite ground reaction force is exerted by the ground on the individual.
10
Q
What is scalar quantity?
A
- when measurements are described in terms of just their size or magnitude.
- distance isn’t taken into account
11
Q
Measurements used in linear motion?
A
- scalar quantities:
- speed
- distance
12
Q
What is speed?
A
- can be defined as the rate of change of position.
- speed in metres per second (m/s) = distance covered in metres (m)/ time taken in seconds (s)
13
Q
What is distance?
A
- the length of the path a body follows when moving from one position to another.
- distance is a scalar quantity as it just measures size.
14
Q
What is the centre of mass?
A
- the point of concentration of mass, of the point of balance of a body.
- the body is constantly moving so CoM will change as a result.
- e.g. raising your arms in the air raises your centre of mass in order to keep the body balanced.
15
Q
What are the factors affecting stability?
A
- the height of the centre of mass: lowering the CoM will increase stability.
- position of the line of gravity: should be central over the base of support to increase stability.
- areas of the support base: the more contact points, the larger the base of support becomes and the more stability increases.
- mass of the performer: the greater the mass, the more stability there is because of increased inertia.
