Biomechanics 3

Front 1

Inertia

Back 1

reluctance of body to change its state of motion. i.e. can still be moving

Front 2

Mass (m)

Back 2

quantity of matter of which a body is composed. Measure of body's inertia. (kg)

Front 3

Force (F)

Back 3

interaction between 2 bodies in push or pull, may/not cause motion. (N)

Front 4

Newton

Back 4

force required to give 1kg mass an acceleration of 1 m/s²

Front 5

Weight (W)

Back 5

attractive force of earth on body. Is a force ∴ a vector.

W=mg g=9.81m/s²

Front 6

Centre of mass

Back 6

Point of which mass of a body is evenly distributed (55-57% of height)

Front 7

Centre of gravity

Back 7

Point at which the weight of a body can be considered to act.

On earth, both are the same.

Front 8

Calculation of centre of mass

Back 8

Cadavers, Math geometric models, Mass scanning

Front 9

Newton's Law of Inertia

Back 9

every body continues in its state of rest, or of uniform motion in a straight line, unless it is compelled to change that state by forces acting on it.

Front 10

Newton's Law of Acceleration

Back 10

change of motion α force applied and is made in the direction of the straight line in which that force is impressed.

F=ma
Newton=kg.m/s²

Front 11

Momentum (p)

Back 11

quantity of motion of a body. (kg.m/s)

p=mv (kg.m/s)
F=p/t (N)

Front 12

Law of action-reaction

Back 12

To every action there is always an equal and opposite reaction

Front 13

Impulse

Back 13

Measure of what is required to change the motion of a body. If a body is acted on by a force (F) during a certain time (time) the body has received an impulse. (N.s)

impulse=Ft

area under force-time curve
impulse=mv(final)-mv(initial)

Front 14

Moment of Inertia (I)

Back 14

resistance of body to a change in angular motion. Depends on distribution of mass w.r.t. axis of rotation.

I=Σmr² (kg.m²)

Front 15

Torque (T)

Back 15

product of magnitude of force and perpendicular distance from line of action of force to axis of rotation (N.m)

T=Fr

Front 16

Law 1:angular analogues of Newton's Laws of Motion

Back 16

Rotating body will continue in state of uniform angular motion unless acted on by external torque

Front 17

Law 2:angular analogues of Newton's Laws of Motion

Back 17

External torque will produce angular acceleration of a body that is directly proportional to torque and indirectly proportional to moment of inertia of body

T=Iα = moment of inertia x angular acceleration

Front 18

Angular Momentum (H)

Back 18

quantity of angular motion of body (kg.m²/s)
H=Iω (ω is angular velocity in rad/s)

Front 19

Conservation of angular momentum

Back 19

remains constant unless an external torque is applied. i.e. decreasing moment of inertia (gymnast tucking) increases angular velocity

Front 20

Law 3:angular analogues of Newton's Laws of Motion

Back 20

For every torque exerted by one body on another body, an equal an opposite torque is exerted.