Biomechanics: Kinetics

What is kinetics?

there term used to describe the causes of movement

What is mass?

the quantity of matter composing a body

What units is mass measured in?

kg or slug

What is inertia?

resistance to a change in a motion

The tendency of a body to maintain its current state of motion, whether motionless or moving with a constant velocity

Inertia

What is the units of measurement for inertia?

Inertia has no units of measurement

Force is characterized by?

by magnitude, direction, and point of application

Force can be thought of as ?

a push or pull acting on a body.

How do you draw force?

as a vector or arrow

Common forces acting on the human body?

gravity, friction, muscle forces, and air resistance

Equation for force?

F=ma

Units for force?

Metric: Newton Imp: Pound

What is a free body?

any object, body or body part that is being focused on for analysis

What is net force?

overall effect of many forces acting on the system (vector sum of forces)

COM is ?

the point around which a boy's mass is equally balanced in all directions

COM is an index of what?

total body motion

COM determines what?

the manner is which the body responds to forces

Can the COM be altered?

Yes, by moving limbs

Weight is the amount of?

gravitational force exerted on a system

Formula for weight ?

w=mg where w=weight m=mass g=acceleration

Units for weight?

Newtons or pounds

Because gravity is different on different planets...

mass is the same but weight is different

Weight always acts...

towards the center of the earth (planet)

Pressure?

Pressure is the force per unit area applied in a direction perpendicular to the surface of an object.

(pushing on table)

Formula for pressure?

P=F/A

Units for pressure?

Pascals or psi

What does Moment of force do?

provides a mechanical advantage

Linear forces are represented by?

Vectors

Axis of Rotation?

Rotation-the arc of motion around a fixed axis of rotation or a "pivot point"

Moment arm?

perpendicular distance between the force and the axis of rotation

Moment of force formula?

M=F*d(upside T)

Example of using moment arm?

loosening a bolt

Why is a moment arm important?

provides a mechanical advantage; using a wrench to loosen a bolt

Joint moment of force

muscles cross each joint, and the linear muscular forces acts to alter the angular rotation of the joint

Rotary force?

is the angular equivalent of linear force; A force is applied to an object causing it to rotate

Moment of force has two determinants?

force and moment arm

Why is moment arm one of the most important concepts in biomechanics?

it measures the ability of muscles to cause rotation