Chapter 7 Equilibrium Flashcards
What is torque
its the rotary (rotation) effect of a force about an axis of rotation
What is moment arm?
it is the perpendicular distance from the force line of action to the axis of rotation
Where do torques occur in the body?
it is the product of muscle tension and muscle moment arm which produces a torque at the joint
What is a lever?
simple machine consisting of a rigid bar that can be made to rotate about an axis or a fulcrum/pivot
What are the classes of levers
1) First Class
2) Second Class
3) Third Class
What is a first class lever?
it is where the fulcrum/axis of rotation is in the middle of the force and resistance
What is a second class lever?
it is where the fulcrum/axis of rotation is closer to the resistance than the force
What is a third class lever?
it is where the fulcrum/axis of rotation is closer to the force than the resistance
What is a mechanical advantage?
it is the ratio of the moment arm of the force over the moment arm of the resistance of a lever
What is the advantage of a force arm > resistance arm?
Require less force to balance a large resistance
What is the advantage of a force arm < resistance arm?
The force can move the resistance in a larger range of motion
What is static equilibrium?
a motionless state where there is no net for or net torque acting on the body
What is Centre of Gravity?
The point at which a body weight is equally balance in all directions (need not be physically located inside of the body)
Why do we have to study CG in human biomechanics?
1) it serves as an index of the total body motion
2) the body responds to external forces as though all masses are concentrated at the CG
3) it is the point at which the weight vector is show to act in a free body diagram
What is stability?
it is resistance to disruption of equilibrium
