• Study of mechanics limited to living especially humans.
• Interdisciplinary, physical and life sciences
• Concerned with laws governing effect of forces on rest or motion in humans

 Statics: all forces acting on a body are balanced.

Dynamics: Deals with unbalanced forces

    (work, energy, acceleration)

Geometry of motion

- Describes time, displacement, velocity and acceleration.

- Motion may be in a straight line or rotating.

Forces that produce change or motion.

- Linear: motion in a line.

- Angular: motion around an axis

Scalar: single quantities

- Described by magnitude (size or amount)

Vector: Double quantities

- Described by magnitute AND direction

Vectors may be broken down into two component vectors acting at a right angle to each other.

Vectors may be combined via + - or * Resulting in a resultant vector

Linear or Translatory

Angular or Rotary

Most motion has a combination of both!

Object is translated as a whole from one location to another.

- Rectilinear: straight line progression

- Curvilinear: curved translatory movement

     - Circular motion: Object moves along circumfrence

Object acting as a radius moves about a fixed point.

Descriptive of motion of the entire radius

Measured as an angle in degrees

Typical of levers, wheels, and axles.

when a ball is held as the arm moves in windmill fashion

- ball is moving with circular motion

- Arm acts as radius moving with angular motion.

Downhill skiing

SEGMENTS primarily undergo angular/rotary motion because joints are axial.

(Negligible translatory motion due to gliding joints.)

WHOLE BODY can undergo linear, rotary, curvilinear and reciprocating movement when acted on by external force.

Rotary: spinning on ice skates, cartwheel?

Curvilinear translatory: diving or jumping

Reciprocation: Swinging on swing

Friction

Air Resistance

Water Resistance

Friction in joints

Tension of antagonists

Ligaments and fasciae

Anomolies of bone/joint structure

Atmospheric pressure

Presence of interfering soft tissues.

Denser objects affected less than less dense objects

Air resistance is increased to equal accelerating force of gravity

-Object no longer accelerating, velocity stays constant

-Vertical velocity must be added

-Height of release may be increased

1. Velocity at time of release
2. Angle of projection
3. Height of release
4. Height of landing 

Rate of rotary displacement

Degrees, radians or revolutions over time in seconds

Marble experiment

Vector

Must identify

-Magnitude

-Direction

-Point of application

Proportionate to # of fibers

Proportionate to size of fibers

Measures force applied by muscle group

Uses anatomical lever

Force resolved into

- X: Mechanical axis (aka non-rotary) which is parallel to the lever and directed toward the fulcrum

- Y: Perpendicular to X (aka rotary)

Changes with motion

When angle of pull is 90 degrees force is...

When angle of pull is 45 degrees force is...

...all rotary

...equal parts rotary and non rotary

Linear: Same or opposite direction (sum forces)

Concurrent: Act at same point of application at different angles. (resultant depends on magnitude and angle)

Parallel: Not in same action line

Ft = m(V_f - V_i)