circular motion Flashcards
what is uniform circular motion?
Uniform circular motion is motion along a circular path in which there is no change in speed, only a change in direction.
what is the nature of speed in uniform circular motion?
constant speed tangent to path
What is the nature of the force in uniform circular motion?
It is a constant force that acts towards the centre
what is needed to change direction in circular motion?
centripetal force is needed
if there was a ball moving in circular motion how would it move?
Ball moves tangent to path, NOT outward
what happens if centripetal force is removed?
When central force is removed, ball continues in straight line.
what is continuously changing in circular motion if the speed of object is kept constant?
speed of the object is constant, it is continuously changing its direction
what is the name given to acceleration in circular motion?
centripetal acceleration
describe centripetal acceleration
acceleration that acts towards the centre of the circular path and is perpendicular to the velocity
what is happening to velocity in circular motion?
velocity is changing because direction is changing therefore causing an acceleration
what is the centripetal acceleration caused by ?
caused by a centripetal force that also acts perpendicular to the direction of motion - newtons second law
equation for linear speed
distance/time m/s
equation for angular speed
angle/time rad/s
linear speed in terms of T (time period)
(2pir)/T
angular speed in terms of T
2pi/T
what is angular displacement
the change in angle, in radians of a body as it rotates around a circle
angular displacement equation
ratio of distance travelled around the circle/ radius of circle
how to convert degrees to radians
ø x π/180 = radians
how to convert from radians to degrees
ø rad x 180/π = degrees
what is angular speed?
the rate of change in angular disaplcement with respect to time
scalar quantity measured in radians per second
equation
for angular speed?
change in angular displacement/time
other equation for angular speed using 2pi as a complete cycle
v/r = 2pi f = 2pi/T
what does the equation of angular velocity tell us?
- the greater the rotation angle ø in a given amount of time, the greater the angular velocity w
- an object rotating further from the centre of circle (larger radius) moved with smaller angular velocity (smaller w)
definition of centripetal acceleration?
acceleration of an object towards centre of circle when an object in motion is rotating around a circle at a constant speed
equation for centripetal acceleration
a = v squared/ r
other equations for acceleration
a = rw squared
a = vw
why do objects have a centripetal force?
an object moving in a circle is not in equilibrium, it has resultant force - centripetal force
definition of centripetal force
the resultant force towards centre of circle requir to keep a body in uniform circular motion, not is always directed towards the centre of the body rotation
is centripetal force a separate force of its own?
no it can be any type of force depending on the situation
what would be the centripetal force if a cat is travelling around a roundabout?
friction between car tyres and the road
what would the centripetal force if a ball is attached to a rope moving in a circle
tension in the rope
what is the centripetal force if the earth Is orbiting the sun
gravitational force
what happens at the top of a circle?
at the top of a circle the weight of the object is directly contributing to the centripetal force because it is acting directly towards the centre
this means that the inwards force such as for a ball being spun on a string is provided by the string - which is at minimum
what happens at the sides of the circle?
the weight of the object acts perpendicular to the direction of centripetal force - meaning it makes no contribution and the force is provided externally
what happens at the bottom of a circle?
the weight of the object is acting opposite to the direction of the centripetal force
inwards face of string must overcome the weight and provide the required centripetal force - meaning its at maximum
what equation can you use to find T if you are given speed and radius
V =( 2pir )/ T
how to find number of rotations in one minute?
angular speed x 60
how do you find angle when given a time and angular speed
angular speed x time period given
