Circular Motion

Question 1

Angular displacement θ

Answer 1

s = rΘ
s arc length
r radius of arc

Question 2

One radian

Answer 2

angle subtended at the centre of the circle when arc length is the same as the radius of the arc

Question 3

angular displacement θ

Answer 3

angle rotated by an object about an axis from its initial angular position to its final angular position

Question 4

Angular velocity ω

Answer 4

ω =δθ/δt

units rad s⁻¹

Question 5

linear velocity v

Answer 5

v = δs/δt
   = δrθ /δt
   =r δθ /δt 
   = rω
units  m s⁻¹

Question 6

Period T of a circular motion

Answer 6

time taken to complete one revolution

T= 2π/ω

Question 7

frequency f of an object in circular motion

Answer 7

number of revolutions the object makes per unit time

f = 1/T
= ω/2π

units Hz or s⁻¹

Question 8

centripetal acceleration a

Answer 8

a = v²/r

= rω²

Question 9

Centripetal Force Fc

Answer 9

Fc = m ac
= mv²/r
= m r ω²