Further Mechanics and Thermal Physics (1): Motion in a Circle Flashcards
What unit is used for angles in SHM and circular motion?
radians
An object rotating at a steady speed is said to be in…?
Uniform circular motion
What is the equation for the linear speed of an object in uniform circular motion?
v = 2(pi)r/T
OR
v = 2(pi)rf
where:
2(pi)r - the circumference of the circle
T - the time taken for the object to complete one full rotation
f - frequency of rotation = 1/T
For a cyclist travelling at speed x, what is the speed of the perimeter of each wheel?
x ms^-1
What is the equation for angular displacement per second?
2(pi)/T
where:
T - the time taken for the object to complete oen full rotation
What is the equation for the angular displacement, theta, of an object in time t?
theta = 2(pi)t/T
OR
theta = 2(pi)ft
where:
theta - angular displacement
2(pi)/T - the angular displacement per second
What is the definition of angular displacement?
The radians swept by an object per second
What is the definition of angular speed, omega (lowercase)?
The angular displacement per second
What is the equation for angular speed?
omega = theta/t = 2(pi)t/T/t = 2(pi)/T
OR
2(pi)f
What is the unit of angular speed?
rads^-1
How do you convert from x radians to degrees?
180/(pi) multiplied by x radians = degrees
How do you convert from y degrees to radians?
(pi)/180 multiplied by y degrees = radians
What is the equation for the linear distance, s travelled by a particle in uniform circular motion in time, t?
s = vt = 2(pi)rt/T = (theta)r
theta = angular displacement in time t = 2(pi)t/T
What is the equation for the linear velocity for a particle in circular motion?
v = 2(pi)r/T = (omega)r
omega = angular speed = 2(pi)/T
Describe why objects in circular motion experience a constant force?
- Objects moving in a circular path are constantly changing direction but moving at a constant speed
- therefore, they have a constantly changing velocity and due to Newtons 1st law an object with a changing velocity is acted upon by a resultant force
OR
- therefore, the object is accelerating and due to Newtons 2nd Law, F = ma, an object that is accelerating must be acted on by a resultant force in the direction of the acceleration