# In which direction does the pseudo force act?

The point O is where the small mass is attached. I'm trying to find out the minimum velocity that should be given to the mass so that it can complete a full circle but if the fixed point is accelerating, how will it affect the answer? What force will act on the particle?

• Can't you just apply the equivalence principle? – João Vítor G. Lima Feb 28 '19 at 14:41
• Uh what is that? I haven't really covered relativity so I don't know how to... – Sameer Thakur Feb 28 '19 at 16:03
• Just consider that the acceleration $a$ becomes a pseudo force field in the opposite direction and you're done. – João Vítor G. Lima Feb 28 '19 at 16:38

To find minimum velocity, we must assume that the tension in the string is 0 at the highest point, hence only the force due to gravity and force due to pseudo force would contribute to the net centripetal force ($$\frac{mv^2}{r}$$). Where v is the velocity at the highest point . In this way the acceleration affects the minimum velocity.