Angular Motion 4.2 Flashcards
What is a Transverse axis and give a sporting example
TA runs from side to side across the body. A somersault rotates a body in a transverse axis
What is a Sagittal axis and where in the body does it occur
(S=stomach) runs from front to back. A cartwheel rotates around the sagittal axis
What is a longitudinal axis and where does it occur
LA runs from top to bottom. A multiple spin in ice skating rotates in a LA
How to remember planes and axis (STFSTL)
Saint (sagittal, transverse), Fiona Shrek (frontal, sagittal), Transport London (Transverse, Longitudinal)
What is rotation ?
Movement around a fixed point/axis
What is angular motion and when does it occur?
Angular motion is when a body part in a circle about a point called the axis of rotation. Occurs when a force is applied outside the centre of mass.
If you apply a concentric force what movement occurs ?
Linear motion
If you apply an eccentric force, what movement occurs ?
Angular motion
What is the name of a turning force ?
Torque
What 2 things does torque depend on ?
- ) size of force
2. ) how far away force is
How do you calculate the moment of force/torque (equation)
Moment of force (Nm) = Force (N) x perpendicular distance from fulcrum (m)
What is the resistance arm ?
Shortest perpendicular distance between fulcrum and resistance
What is the effort arm ?
Shortest perpendicular distance between fulcrum and effort
What is Newton’s first law linear ?
Everybody continues in its state of rest or motion in a straight line, unless compelled to change that state by an external force acting upon it
What is Newton’s first law angular ?
Everybody continues in its state of rest unless compelled to change that state by an external rotational force acting upon it.
What is Newton’s 2nd law linear ?
Rate of change of momentum (acceleration) of a body is proportional to the force causing it and the change that takes place in the direction which the force acts
What is Newton’s 2nd law angular motion ?
Rate of change of angular momentum of a body is proportional to the force causing it and change that takes place in the direction which force acts
What is Newton’s 3rd law linear ?
When a force is applied by one body to another, the second body will exert an equal and opposite force on the other body.
What is Newton’s 3rd law angular?
When a force is applied by one body to another, second body will exert an equal and opposite force on the other body
Give an example of Newton’s 1st law in practise AM
Ice skater spinning in the air, continue to spin until they land on the ice when an external force (torque) is exerted from the ice on their skates which changes their state of angular momentum
Give an example of Newton’s second law AM
The greater the torque exerted, the faster the rotation will be, Golf swing
Give an example of Newton’s 3rd law in practise AM
A goalkeeper tips the ball over the bar, they throw their arms up and back (eccentric action force on the body), which causes the lower part of their legs to come up and forward (reaction force)
What is the equation for angular velocity ?
Always divide degrees by displacement 57.3
Angular velocity= angular displacement (divided ) time taken
What is the equation for angular acceleration
Angular acceleration = change in angular velocity (divided) time taken (s)
What are the 2 factors that are dependent on moment of inertia ?
Mass of the object
How the mass is distributed from point of rotation
Factors moment of inertia to mass of the object
Greater mass, greater resistance to change and therefore greater the moment of inertia.
Moment of inertia : distribution of mass from axis of rotation
Closer the mass to the axis of rotation, smaller the inertia, easier to then rotate
What happens if you increase the distance of the distribution of mass from the axis ?
The moment of inertia will increase but make rotation slower
What is the equation for angular momentum ?
Angular momentum = angular velocity x money of inertia
L= W x I
Moment of inertia increases , angular velocity decreases
What is the conservation of angular momentum ?
- ) of mass moves closer to axis of rotation moment of inertia decreases & angular velocity increases because angular momentum is conserved
- ) If mass moves away from axis of rotation moment of inertia increases & angular velocity decreases because angular momentum is conserved
