Week 2- Newtons Laws and Impact of Internal and External Forces on Movement Flashcards
1st: Law of Inertia
A body remains at rest or at a constant linear velocity except when compelled by an external force to change its state (body stays at equilibrium)
Inertia
Amount of energy required to move a body
2nd: Law of Acceleration
- The linear acceleration of a
body is directly proportional to the force causing it, it
take place in the same direction in which the force acts and is inversely proportional to the mass of the body - F (force) = M (mass) x a (acceleration)
3rd: Action/Reaction
For every action there is an equal and opposite reaction
Examples of law of inertia in PT
Perturbation training
Examples of law of acceleration in PT
Resistance exercise
Examples of action/reaction in PT
MMT break tests/isometric exercises
Internal Forces
Forces produced within the body for movement or stabilization
Active Force
Muscle contraction
Passive Force
Stretch of soft tissue
External Forces
Forces acting on the body by an outside source, the body must overcome or react to these forces to achieve a specific outcome
Joint stability
ability to maintain or control joint position and movement
What role do muscles play in joint stability?
- Restricting the movement of certain joints
- Produce the desired action
- Increasing joint compression
- Usually occurs with co contraction of synergist muscles that surround a joint
(compression and increasing joint stiffness)
Closed Chain Exercises
Activities in which the distal
segment is fixated and is not free to move in space
Open Chain Exercises
Activities in which the distal segment in not fixated and can move in space
