Angular Motion Flashcards
Define angular motion
Movement of a body or part of a body in a circular path about an axis of rotation
What is an eccentric force
A force applied outside the centre of mass, resulting in angular motion
Define torque
A measure of the turning (rotational or eccentric) force applied to a body
Define a principle axis of rotation
An imaginary line that passes through the centre of mass about which a body rotates: longitudinal, transverse and frontal axis
What is the longitudinal axis and give a sporting example
Runs from head to toe though the centre of mass
Ice skater performing a jump with spin
What is the transverse axis and give a sporting example
Runs from left to right through the centre of mass
Somersaults
What is the frontal axis and give an example
Runs from front to back through the centre of mass
Cartwheels
What is a Radian (rad)
A unit of measurement of the angle through which a body rotates
360° = 2π radians, 1 radian = 57.3°
Define angular velocity and give the calculation and units
The rate of change in angular displacement (rad s-1)
Angular velocity = angular displacement ÷ time taken
Define moment of inertia (MI)
The resistance of a body to change its state of angular motion or rotation
List and explain the factors affecting moment of inertia
• mass - the greater the mass, the greater the moment if inertia
• distribution of mass - the further the mass moves from the axis of rotation, the greater the moment of inertia
Define angular momentum and give the calculation
The quantity of angular motion possessed by a body
Angular momentum = moment of inertia × angular velocity
What is the angular equivalent of Newtons first law of motion
A rotating body will continue to turn about its axis of rotation with constant angular momentum unless acted upon by an eccentric force or external torque
