Week 4 - Angular Kinematics, Levers and Torque Flashcards
Linear velocity formula
change in displacement/change in time
Angular velocity formula
change in angle/change in time
Linear acceleration formula
change in velocity/change in time
Angular acceleration formula
change in angular velocity/change in time
Linear displacement
change in linear position
Angular displacement
change in angular position
What is linear inertia?
a body will remain at rest or in constant motion unless acted upon by a net external force, resistance of a body to changes in its motion
What is angular inertia (moment of inertia)
resistance to angular motion
Angular inertia (moment of inertia) formula
moment of inertia = mass x radius of gyration
What is the radius of gyration?
how the mass is distributed with respect to the axis of rotation; distance from the axis to the COM
What is linear momentum?
quantity of motion possessed by a body
Linear momentum formula
mass x velocity
How is angular momentum changed?
change the impulse (force applied over a period of time)
What is impulse
force applied over a period of time, force x time
Impulse formula
force x time
What are the three types of levers in the body and an example for each?
- lever systems (biceps brachii pulling on radius)
- wheel and axle systems (rotator cuff muscles pulling on humerus)
- pulley systems (patella)
What is a lever?
a rigid structure hinged at one point with forces applied at another point
What is a first class lever?
lever of balance, head balancing on spine, fulcrum in middle
What is a second class lever?
lever of strength, standing on toes, resistance in the middle
What is a third class lever?
lever of speed and ROM, bicep curls, effort in the middle
What is mechanical advantage?
- amount of one to overcome the other
- based on distance (moment arm) forces are from fulcrum
- length of effort arm vs length of resistance arm
What is the formula for mechanical advantage?
effort arm/resistance arm
What is torque?
turning effort produced by a force, force is applied away from COM/axis of rotation
What is the formula for torque?
applied force x moment arm