Applying Newton's laws to angular motion Flashcards
What is Newton’s 1st law of ROTATION?
Law of inertia - an objects resistance to change its state of motion whilst rotating
Give an example of Newtons 1st law in rotation
An ice skater will continue to rotate in the air until they land. Here the ground exerts an external force (torque) which changes their state of angular momentum. A decrease in angular velocity around their longitudinal axis
What is a rotational force also known as?
An eccentric force or a torque
Define angular motion
Movement around a fixed point or axis
What is Newtons 2nd law of ROTATION?
Law of acceleration - the rate of change of angular momentum is directly proportional to the rotational force (torque) acting on it
Give an example of Newtons 2nd law of rotation
The faster a diver throws their head and arms forwards off a diving board, the greater their angular velocity will be around their transversal axis
What is Newtons 3rd law of ROTATION
Law of action/reaction - for every rotational action there is an equal and opposite rotational reaction
Give an example of Newtons 3rd law of rotation
When a netballer is stretching over a shot, their arms go upwards and fowards (anticlockwise) whereas their legs go backwards and upwards (clockwise)
Define angular displacement
The smallest change in angle between the start and finish point
What is a radian?
53.7 degrees
What is the equation for angular velocity?
Angular velocity (rad/s) = angular displacement (rad) / time taken (s)
Define angular acceleration
The rate of change of angular velocity
What is the equation for angular acceleration?
Angular velocity (rad/s) / time taken (s)
It takes an ice skater 0.3 secs to rotate 140 degrees on the ice
a) calculate their angular velocity
b) calculate their angular acceleration
a) 140 / 57.3 = 2.4
2.4 / 0.3 = 8 radians/sec
b) 8/0.3 = 26.7 radians/sec squared
What are the three axis?
- Transversal = somersault
- Sagittal = cartwheel
- Longitudinal = pirouette