Circular Motion Flashcards
What is angular velocity
The Angular Velocity is the Angle an Object Rotates Through per Second
What is the equation for angular velocity
ω= θ/t
w is angular velocity measured in radians per second
What is the equation linking linear and angular velocity
V= rω
Where v is linear velocity (ms^-1)
r is the radius of the circle (m)
ω angular velocity (rads^-1)
What is frequency
Frequency is the number of complete revolution per second (revs^-1 or hertz)
What is period
The time taken (in seconds) for a complete revolution
What is the equation linking frequency and period
f=1/T
What is the equation for angular velocity involving frequency and period
ω=2pi/T
ω =2pif
What is the equation for angular velocity involving frequency and period
ω=2pi/T
ω =2pif
Why is a car going at a constant speed around a roundabout at a constant speed said to be accelerating
It velocity is changing because it direction is changing.
Since acceleration is defined as the rate of change in velocity over time the car is accelerating even though it isn’t going any faster.
What is the acceleration of an object going in circle called, and where is it directed to
Centripetal acceleration and it is always directed to the cente of the circle
What is the formula to calculate centripetal acceleration
a=v^2/r and a= ω^2 r
V is linear velocity
ω is angular velocity in rad s^-1
r = radius in m
What law explains why there must be a centripetal force
Newtons 1st law (if an object is accelerating there must be a net force acting on it)
What is the force that allows an object to travel in a circular path
An object will travel in a circular path if there is a net force acting on it perpendicular to the velocity. This is called centripetal force and it always act towards the centre of the circle.
What are the equations to calculate centripetal force and why do these make sense
Since F=ma
F=mv^2/r
F=m ω^2 r
What would happen if the centripetal force stopped being applied
The object would fly off at a tangent
What happen to the kentic energy as the object spins round
Although the force changes direction, the objects velocity remains perpendicular to the direction of the force. The object never moves towards or away from the centre of the circle, so there is now motion in the direction of the force. Hence no work is done on the object, and therefore the kinetic energy (and therefore speed remain constant)
In simple harmonic motion, what does displacement refer to
The distance of the object from the midpoint (which the object is oscillating about)
Describe the movement of an object moving with similar harmonic motion, with example
An object moving with simple harmonic motion (SHM)
Midpoint
oscillates to and fro, either side of a midpoint.
Pendulums and mass-spring systems (e.g. a mass hanging on a spring that’s free to move up and down) are two examples.
State the condition needed for movement to be simple harmonic
Condition for SHM: an oscillation in which the acceleration of an object is directly proportional to its displacement from the midpoint, and is directed towards the midpoint.
Describe the resultant force on an object in moving in simpler harmonic motion
There is always a restoring force pulling or pushing the object back towards the midpoint.
The size of the restoring force depends on the displacement, and the force makes the object accelerate towards the midpoint.
