# Why Pseudo/Fictious Forces act at centre of mass [duplicate]

I was reading about torque and pseudo forces and my book says that the torque about centre of mass for a Pseudo/Fictious force is zero.

I cant really get that as it is non-intuitive for me .

Can someone explain it in a simple manner.

Any help is appreciated

## marked as duplicate by AccidentalFourierTransform, ZeroTheHero, Jon Custer, ja72, peterhApr 27 '17 at 2:48

• Possible duplicate of Why does gravity act at the center of mass? – AccidentalFourierTransform Apr 26 '17 at 16:33
• This is definitely not true for the Coriolis or centrifugal force; they can exert torques about the CM. If you're only considering fictitious forces due to uniform linear motion, then check out the question linked by AccidentalFourierTransform above, especially this answer; the logic is the same as it is for a uniform gravitational field. – Michael Seifert Apr 26 '17 at 16:48

While we sometimes think of things as pseudo-forces, they're really better thought of as accelerations (note: I don't have to call them pseudo-accelerations). The pseudo-forces are all results of using non-inertial frames*, which means they have an acceleration term which accounts for the non-inertial effects. For example, the "centrifugal force" in a rotating frame is more accurately a "centrifugal acceleration of $\frac{v^2}{r}$. This term can be derived directly from the change of frame from inertial to rotating, using calculus.