Instantaneous Centre Technique:
We have seen that a body undergoing plane motion contain two components:
1. Translational component, and
2. Rotation component.
Further, we may imagine a point (may be outside the body sometimes) about which the body appears to rotate, i.e. the translation motion of this point is zero. Such a point is called as instantaneous centre of rotation.
Consider a body undergoing plane motion. vA and vB are velocities of two points A and B at any instant as shown in Figure.
![1585_Instantaneous Centre Technique.png](https://www.expertsmind.com/CMSImages/1585_Instantaneous%20Centre%20Technique.png)
Draw perpendiculars to vA at A and to vB at B. These two perpendiculars meet at O. Then O is called as the instantaneous centre of rotation also known as instantaneous centre of zero velocity.
Then we have
v A = vO + vOA vOA = AO ω (Perpendicular to OA)
v B = vO + vOB vOB = BO ω (Perpendicular to OB)
This is possible when vO = 0 .
∴ O is instantaneous centre