2A - Forces

Define Linear motion

• motion in a straight line or curved line

• all body parts move in same direction simultaneously

define Angular motion

• motion around an axis of rotation

• body parts move in circular path

define Mass

• measures amount of matter in a body

• is constant

• represents objects resistance to change in motion

define Force

• is a push or pull to cause an object to change its motion

• generally acts in a straight line

define torque

• its an angular motion caused by a force exerted outside its centre of gravity/axis

• T=length of lever arm x Force

difference between velocity and speed

• refers to the distance/time taken

• speed does not have a direction

• velocity is displacement/time taken

• velocity has a direction (positive - left, negative - right)

define linear momentum

• how much motion an object has

• P=mv

relationship between momentum and mass/velocity

• more mass = greater momentum

• more velocity = greater momentum

• object with more momentum will be more difficult to slow down/stop

define conservation of momentum

• momentum is conserved at impact

• momentum is not lost, it is transferred

• object will transfer its momentum when in a collision with another object

define impulse

change of momentum

ΔP= force x time

to change or create momentum…

• move faster to increase velocity, increasing momentum

• move slower to decrease velocity, decreasing momentum

define moment of inertia (MOI)

• measure of how resistant an object is to its change in rotational motion

• Angular momentum = MOI x angular velocity

define summation of forces

• refers to the correct timing and sequencing of body parts to produce maximal force

define sequential force summation

• refers to when body parts are moved in sequence

• moving from largest body part to smallest body part to generate greater force

4 force summation principles to produce maximal force

1. use as many body parts as possible

2. sequence

3. stabilization

4. timing

B.E.S.T

describe the first step to summating momentum

• use as many body parts as possible

describe the second step to summating momentum

• start with larger body parts and muscle groups to generate the most force and stability

• followed by lighter and smaller muscle groups

describe the third step to summating momentum

• body parts must stabilise before transferring momentum as so momentum is not lost during movement

describe the fourth step to summating momentum

• move next body part only when the previous body part has reached maximal velocity

• to generate most force

describe newtons first law

• law states that a body will remain at rest or in uniform motion unless acted on by an external object

define inertia

• defined as the tendency of an object to resist its change in motion

relationship in law of inertia

• greater mass, greater inertia

• less mass, less inertia

describe newtons second law

• law states that as force is applied to an object it will produce a change in motion in the direction that the force is applied, which is directly proportional to the size of force

define acceleration

• is the rate of change in a objects speed with direction and magnitude

describe newtons third law

• law states that for each action there is an equal and opposite reaction

relationship for law of acceleration

• greater force, greater acceleration

• greater mass, less acceleration

• F=ma

relationship in law of action-reaction

• forces that are equal and opposite do not cancel out

• due to each force will be dependent on objects acceleration and mass