# The length of a seconds hand in a watch is 1 cm. Magnitude of change in velocity of its tip in 15 sec is?

##
A: 0 cm/sec

B: #(pisqrt2)/60#

C: #pi/30#

D: #(pisqrt2)/30#

The answer is D for your reference

A: 0 cm/sec

B:

C:

D:

The answer is D for your reference

##### 1 Answer

The seconds hand of the watch rotates

The angular velocity of its tip will be

Let the initial position of the tip of the seconds hand be at 12 in the watch. At this position the direction of the velocity of its tip will be towards positive direction of X-axis (considering center of rotation as origin).After 15s the tip rotates

Initial velocity vector

Final velocity vector

So the change in velocity during 15s will be

So magnitude of change in velocity will be

#=sqrt(v^2+v^2)#

#=sqrt2 v#

#=(sqrt2 pi)/30# cm/s