Circular motion Flashcards
(13 cards)
Why is an object in uniform circular motion continuously accelerating?
An object in uniform circular motion has a constant linear speed. However, it is continuously changing direction. As velocity is a vector quantity (takes both direction and magnitude into account), the velocity is also continuously changing.
As acceleration is change in velocity with respect to time, an object in uniform circular motion is continuously accelerating
What is the acceleration in an object with uniform circular motion called?
This acceleration is known as centripetal acceleration and is perpendicular to the direction of linear speed.
Centripetal means it acts towards the centre of the circular path
How are the centripetal force and acceleration related?
The centripetal acceleration is caused by a centripetal force of constant magnitude that also acts perpencidular to the direction of motion.
This is a result of Newton’s second law. The resultant force (F=ma) is in the same direction as the acceleration
What is angular displacement?
The change in angle, in radians, of a body as it rotates around a circle
How do you calculate angular displacement?
Angular displacement = distance travelled around the circle / radius of circle
Δθ = s / r
What is 1 radian equal to?
The angle subtended at the centre of a circle by an arc equal in length to the radius of the circle
How to convert degrees to radians
θ rads = θ x (π / 180)
How do you calculate angular velocity?
ω = Δθ / Δt
ω = v / r = 2πf = 2π / T
v = linear speed
r = radius of orbit
T = time period
f = frequency
What is centripetal acceleration?
The acceleration of an object towards the centre of a circle when an object is in motion (rotating) around a circle at constant speed
How do you calculate centripetal acceleration?
a = v2 / r
a = r x ω2
a = vω
What is the centripetal force?
The resultant force towards the centre of the circle required to keep a body in uniform circular motion. It is always directed towards the centre of the body’s rotation
How do you calculate centripetal force?
F = mv2 / r = mrω2 = mvω
What is the centripetal force in different scenarios?
The centripetal force is not a seperate force of its own. It can be different forces in different scenarios
Car travelling around a roundabot : friction between car tyres and road
Ball attached to a rope moving in a circle : tension in the rope
Earth orbitting the sun : gravitational force
