Biomechanics

Question 1

Inertia

Answer 1

An object will remain at constant rest or constant motion unless acted upon by an external force
(resist change unless force applies)

Question 2

Moment of inertia

Answer 2

Measure of the unwillingness of an object to rotate (heavy objects - more unwilling)

Question 3

Friction

Answer 3

With relation to a grip of two surfaces together. More grip - enhanced friction, Less grip - less friction (trainers on hall floor = great friction, socks on hall floor = slippy/less friction

Question 4

Force

Answer 4

A force (push or pull) when applied has ability to move an object
Force = Mass x Acceleration

Question 5

Momentum

Answer 5

Measure of the amount of motion an object has and its resistance to changing that motion

Momentum = Mass x Velocity

Question 6

Summation of momentum

Answer 6

Actions requiring multiple joints requires summation of momentum, meaning that multiple parts of the body channel momentum to ultimately result in maximum velocity (golf swing = lower body, shoulders, arms wrist)

Question 7

Impulse

Answer 7

Impulse = Force x Time

Required to change momentum of an object, force applied over period of time

Can work positively (shot putter generating force over time to throw far)

Or negatively (catching fast ball, bringing into body and decreasing build up momentum by counteracting, smothering force)

Question 8

Newton’s Laws

Answer 8

1st Law (law of inertia)
'A body will remain at constant rest or motion in a straight line unless acted upon by external force'

2nd Law (law of acceleration)
'A force applied to an object will produce a change in motion (acceleration) in the direction of the applied force' 
More force necessary to move objects with greater inertia (heavier objects)
Force = Mass x  Acceleration 

3rd Law (action-reaction)
'For every action there is an equal and opposite reaction'
(foot presses down on track = track bounces back, foot presses down on sand = force spread on sand as result)

Question 9

Angular Motion

Answer 9

Product of moment of inertia and angular velocity of an object rotating around an axis

(hand on a clock rotating in circular motion around an axis [creates angles])

*As per Newton’s Law, except torque used

Question 10

Torque

Answer 10

Rotational force (push or pull) that makes an object rotate

Question 11

Projectile motion

Answer 11

Object launched into the air and affected by only gravity and air resistance = projectile

Projectile motion = factors that influence the flight path of a projectile

• Angle of release
• Speed of release *factors affecting
• Height of release flight path

(balls, arrows, javelin, shot put)

Question 12

Levers

Answer 12

Machine consisting of a rigid bar made to rotate around an axis to apply a force

Levers make it easier to move a external resistance by applying a force which counteracts (arm lifting dumbell, arm = force, dumbbell = resistance)
(longer lever = more efficient)

Axis (pivot joint)
Resistance (weight to be moved)
Force (necessary effort applied to move)

*Human body consists of a majority of third-class levers

Question 13

Centre of gravity

Answer 13

Centre of gravity is the location which an object’s weight is balanced (this can be manipulated)

When changed this can increase/decrease stability
(runners on blocks want to decrease to push centre of gravity out of body and begin to propel them before a start of the race)