# How to find pseudo-force on a body in a non-inertial reference frame with respect to another non-inertial reference frame?

If there is a body in a non-inertial reference frame (say accelerating with acceleration $$A_1$$) and an observer in another non-inertial reference frame (say accelerating with acceleration $$A_2$$) what would be the pseudo-force acting on the body (say it has mass $$m$$) as seen by the observer? Both $$A_1$$ and $$A_2$$ are in the same direction and along a straight line.

Do I simply need to find the relative acceleration of the first frame with respect to the second frame and multiply the relative acceleration with the mass of the body?

• I'm not sure if I understand your question but The inertial force a body feels from acceleration is independent of what other bodies are doing. Commented Sep 21, 2016 at 0:01
• Okay, that means it doesn't depend on what an observer sees. Is it true for all kinds of forces acting on a body? i.e. independent of what an observer sees from another reference frame? Commented Sep 21, 2016 at 3:45

Therefore, given that the acceleration of the observer is $$A_2$$ the pseudo force acting on any body (which has mass $$m$$) observed will be $$-m \cdot A_2$$.