If Any object moves such that it covers an angle q at the fixed point (center of the circle) and its gap from the fixed point remains constant (radius of the circle)


Here R is constants



Now finding linear speed of

(i) hour hand (30 cm)

(ii) Minute hand (90 cm)

(iii) Second hand (60 cm)

Solution:- (i) time period of hour hand T = 12 hr

               = 12 x 3600 sec

                                                                v = r w


(ii) Minute hand:- time period = T = 60 min = 60 x 60 sec


(iii) Second hand:-

Time period= T = 60 sec

v = r w

Types of circular motion: (on the basis of speed)

(1) Uniform circular motion: (U C M)

Only direction of velocity is changing, magnitude remains unchanged.


Now acceleration due to change in direction of velocity

Using law of parallelogram




= 2v2 - 2v2 cosq                                 

= 2v(1- cosq)






sinq » q if  q <<<<



a = v w,




Direction of this acceleration is towards center


Centripetal acceleration or Radial acceleration

(2) Non uniform circular motion (Non U C M)

Here in this case direction as well as magnitude both are changing continuously therefore here two different named acceleration will be as,

(i) ac = aR (centripetal or radial acceleration)

(ii) at (Tangential acceleration)


Tangential acceleration. 

Rate of change of magnitude of velocity”

v = R w




So at ^ ac


Net acceleration for non-uniform circular motion.

Example:- A particle moving in a circular path of radius 2 meter and its velocity varies as  v = 10t2. Then net acceleration of the particle at t = 2 sec.

Solution: Given v = 10t2


= 20 x 2

= 40 m/s2



Centripetal force:- the force require to move in a circular path for any object with respect to inertial frame is called centripetal force.


Note:- Centrifugal force will also have same magnitude but direction opposite to centripetal force.

Direction of this force is towards the center.


(1) Only banking

Here N sinq is C.P. provider


But N cosq = mg



            Safe speed

(2) Only friction 

Here now m N is C.P. provider


N = mg




Safe speed

Friction and Banking both:- To prevent inward sliding

 cosq + m N sinq = mg




N cosq - m N sinq = mg



v1 < Vsafe < v2


T sinq = mrw2

T cosq = mg



Time period of conical pendulum