Kinetics Flashcards
Biomechanics
Internal vs. External Forces
Kinetics
Internal Forces are either actively or passively produced from structures located within body
External Forces are produced by forces acting from outside body
Biomechanics
What is the relationship between internal and external torque during a isometric contraction?
Kinetics
Internal Torque = External Torque
Biomechanics
What is the relationship between internal and external torque during a concentric contraction?
Kinetics
Internal Torque > External Torque
Biomechanics
What is the relationship between internal and external torque during a eccentric contraction?
Kinetics
External Torque > Internal Torque
Biomechanics
What is the formula for force (N)?
Kinetics
mass (kg) x acceleration (m/s^2)
Biomechanics
What is the formula for pressure (Pa)?
Kinetics
force (N) / area (cm^2)
Biomechanics
What is inertia?
Kinetics
Inertia is the tendency to resist change in state of motion. It is proportional to mass and has no units.
Biomechanics
What is centre of mass (gravity)?
Kinetics
The center of mass (gravity) is the point around which a body’s weight is equally balanced in all directions. This serves as the index of total body motion and is the point at which the weight vector acts.
Biomechanics
What would happen to the body’s overall Center of Mass if a person had a below knee amputation on the right leg ?
Kinetics
Their Center of Mass would shift left and up.
Biomechanics
What is torque?
Kinetics
The product of force and the perpendicular distance from the force’s line of action to the axis of rotation (T = Fd)
Biomechanics
What is a force couple?
Kinetics
A pull where two or more muscles produce forces in different linear directions but the same rotary direction.
Example: lower trapezius + upper trapezius + serratus anterior = Upward Rotation
Biomechanics
What is impulse?
Kinetics
The product of force and the time during which the force acts (Ft)
Biomechanics
What are the angular equivalents of mass, force, momentum and impulse?
Kinetics
1) Mass = moment of inertia
2) Force = Torque
3) momentum = angular momentum
4) impulse = angular impulse
Biomechanics
Stress vs. Strain
Kinetics
Stress is the force generated as a tissue resists deformation, divided by its cross-sectional area
Strain is the ratio of a tissue’s deformed length to its original length
Biomechanics
What is Viscoelasticity?
Kinetics
Viscoelasticity is the property of a material expressed by a changing stress-strain relationship over time
Biomechanics
What is Deformation?
Kinetics
Change in shape:
- Elastic region
- Yield point
- Plastic region
- Ultimate failure point
(May be either temporary or permanent)
Biomechanics
What is Creep?
Kinetics
A progressive strain of a material when exposed to a constant load over time.
Biomechanics
What is Hysteresis?
Kinetics
When a viscoelastic material is loaded and unloaded, the unloading curve is different from the loading curve. If loading and unloading are repeated several times, different curves can be obtained. The results is increased elongation at a similar load.
Biomechanics
What is Tension?
Kinetics
Pulling or stretching force directed axially through a body
Biomechanics
What is Shear?
Kinetics
Force directed parallel to a surface
Biomechanics
What is Bending?
Kinetics
Asymmetric loading that produced tension on one side of a body’s longitudinal axis and compression on the other side.
Biomechanics
What is Torsion?
Kinetics
Load producing twisting of a body around its longitudinal axis
