Chapter 3
Sir Isaac Newton’s 3 Laws of Motion
1. (inertia) An object at rest stays at rest, and an
object in motion stays in motion unless acted
upon by another force
2.
The amt. of acceleration an object has when
you apply a force to it is proportional to the
amount of force applied and inversely
proportional to its MASS,
3. For every action there is an equal and opposite
reaction. e.g. pushing off floor during walking
– push down and back, you go forward and up
Infants push more down than back and move
slower as a result.

Rotational force to linear force
The objects linear velocity= rotational velocity
and radius of rotation (thus a longer arm =
greater force production)
Shorter limb length = less resistance to motion
Thus to produce a quick throw you need a
compact motion
To produce the greatest force you need a long
motion.
(e.g. javelin vs baseball)
Ice skater
Batter compact swing to start, full extension on
contact

Force Absorption – the impact of a force is affected
by the time over which the impact occurs and the
area that the impact effects.
 Knees bending decreases impact of jump
 Knees straight increase impact of jump
 “Giving” with ball
 “Giving” with collision
---Stability= resistance to movement (large heavy box)
--Balance= the ability to maintain equilibrium (equal
distribution of wt.) around the Center of Gravity (CG)
--Larger the base of support(BOS)=greater balance and
stability
--Balance = CG being over the base of support
--The lower the CG is to the BOS, the more stable one
is.

In Locomotor Skills
--You sacrifice stability in order to move
--Alternating losing and gaining balance
from one foot to the other
--CG is pushed out over the BOS, and then the
individual quickly moves his other leg forward
to regain balance (dynamic balance).
Website Document (Movement Principles)
 Using Principles to Detect and Correct Errors
1. Complete and full observance of the movement
(technology)
2. Analyze each phase and its key elements
3. Break it down into parts (kinetic chain)
4. Use movement principles to analyze the
movement
Can you improve stability?
Kinetic chain sequence?
Release Point?
Correct errors through isolation and repetition
