Chapter 8 (Basic Biomechanics) Flashcards
(48 cards)
What does biomechanics involve?
Taking the principles and methods of machines and applying them to structure/function of the human body
Factors associated with non-moving systems
Statics
Factors associated with moving systems
Can be divided into kinetics, kinematics
Dynamics
Deals with forces causing movement in a system
Kinetics
What does kinematics deal with ?
Deals with forces involved in time, space, and mass aspects of moving system.
(Osteokinematics + arthrokinematics)
What is osteokinematics?
Deals with the manner in which bones move in space.
Without regard to the movement of joint surfaces
What is arthrokinematics?
Deals with the manner in which adjoining joint surfaces move in relation to each other
(In the same or opposite direction)
What is force?
Any action or influence that moves an object
The amount of matter that the body contains
Mass
The property of matter that causes it to resist any change of its motion in either speed or direction
(Mass is a measure of inertia)
Inertia
What is torque?
the tendency of force to produce rotation about an axis
Force developed by 2 surfaces
- Tends to prevent motion of one surface across another
Friction
What are the 3 laws of motion?
- Law of Inertia
- Law of Acceleration
- Law of Action-reaction
Which law is this:
An object at rest tends to stay at rest, and an object in motion tends to stay in motion
Law of Inertia
Ex. Arm will not bend without the force of the muscle
Describe the law of Acceleration
- the amount of acceleration depends on the strength of the force applied on an object
Ex. Kick 2 balls same size; the harder kick will go further - Acceleration is inversely proportional to the mass of an object
Ex. Kick 2 balls w/ same amount of force; ball w/greater mass will not travel as far
Describe the law of Action-Reaction
For every action there is an equal and opposite reaction
Ex. As you jump down on a trampoline, the trampoline pushes back with the same amount of force
What is needed to create force?
One object must act on another
What are the 3 characteristics of force?
- Magnitude
- Direction
- Point of application
When two or more forces are acting along the same line or plane.
Linear force
Ex. *pulling a boat
*Pushing a bed on same side
*2 people on opposite sides of a bed, pushing w/same force = no motion
Occur in the same plane and direction with a counter force in the middle but in the opposite direction
Parallel forces
Ex. seesaw
Describe a resultant force
Net effect of 2 divergent forces
Lies somewhere in-between
Occurs when two or more forces act in different directions, resulting in a turning effect
Force couple
What is an ex. of force couple?
Unscrewing a jar lid
Force A= fingers
Force B= thumb
What is torque ?
Moment of force; ability of force to produce rotation about an axis