Question

A vector of length 'a'is turned about its tail through an angle ' α'.Then what will the magnitude of the difference in the position vector?

Answer 1

As the vector has been rotated by angle theta,

Let the final vector be called as vf , while the initial being vi 

The magnitude of change in vector is | vf  – vi | = ( vi2 + vf2 - 2vivfCos(theta))^0.5

as the magnitude is same say ‘v’

thus the expression reduces to 2vSin(theta/2)

 

Kindly note that change in magnitude is zero while magnitude of change in vector is 2vSin(theta/2)

Hope this rustic expression is not that pesky.

Hope it helps u!!