F=-dU/dx

where U is the potsntial energy of the body.

now consider a situation : a [b]ball is thrown upward [/b] with a certain [b]finite velocity [/b] (no other non-conservetive force acts on it , [b]neglet air friction[/b])

when the ball is at the [b]top of its trajectory [/b] i.e. we can equally say that its [b]kinectic energy is zero or its potential energy is maximum[/b].REMEMBER [b]GRAVITAIONAL FORCE IS STILL ACTING ON THE BALL[/b].

F=-dU/dy

so acc to the form mentioned above [b]U is max so force acting on the ball should b zero [/b] but obviously gravity is still acting.

SO WHERE THE [b]FALLACY[/b] LIES???????????