Have a look at this question, and the attached image file for the figure:

A uniform bar ABC has mass m and starts from rest with 𝜃 = 180 degrees where A,B,C and O are collinear. If applied force P is constant in magnitude and always perpendicular to AC in the direction shown, determine the angular velocity 𝜔 of the bar when 𝜃=120 degrees. Apart from the bar, every other element is mass-less.

enter image description here

so my query is, how do i even start writing the equations? had the force been acting in a constant direction i could have taken components and then solved them all but here the force changes directions every time!

Even if i write the equation for the force at some time, it will have changed direction the very next moment and my analysis will not hold at that moment!

  • $\begingroup$ To be honest I can't think how was the initial condition established! You said ABCO are colinear bot with that rod type hinge between O and C how is it possible? $\endgroup$ Apr 8, 2017 at 8:50
  • $\begingroup$ Let us continue this discussion in chat. $\endgroup$ Apr 8, 2017 at 8:53