1. ACTION/REACTION FORCES
body segments exert a force
environment delivers reaction force
Newton’s Third Law
for every force applied on a body
that body applies an equal & opposite force

2. T = F x FA
F is board reaction
FA is d 
t is board recoil time

3. Internal Forces External Forces
within defined body
body free of support
muscles contractions change body shape
c of g position NOT changed
outside defined body
body in contact
muscle contractions change body position
c of g position CHANGED

4. Motive Forces Resistive Forces
cause Motion
muscle, pull of gravity buoyancy
concentric contraction
friction
fluid lift
oppose/resist Motion
muscle, connective tissue
eccentric contraction
friction
fluid drag

5. FORCE and PRESSURE
Force - push, pull, blow, rub that changes a body’s motion or shape
pressure - amount of force acting over area
p & F direct relationship, p & A indirect

6. FRICTION FORCE Force created between 2 contacting surfaces
can be a Motive or a Resistive Force
texture of surfaces [rough = more friction]
force pressing together the 2 surfaces
size of surface area NOT a factor
high coefficient of friction = low slippage

7. CENTRIPETAL FORCE Center seeking
forces rotating body to stay on a circular path
if Fc is insufficient, body will leave path on a tangent

8. ELASTIC FORCE Recoil ability
measure of how quickly reformation follows deformation
coefficient of elasticity = square root of rebound ht/dropped ht
high e = faster reforming

9. BUOYANCY FORCE upward lift Force on a body immersed in a fluid
Archimedes Principle
upward buoyant F = wt of volume of water displaced
Negative Buoyancy - body wt. greater than the wt. of the volume of water displaced

10. POWER
P = Force x velocity
P = Force x distance/time

11. ENERGY: the ability to do work
Kinds of Energy
1. chemical
2. electrical
3. heat
4. mechanical
3 types of Mechanical E
1. Elastic
2. Gravity - Potential
3. Kinetic