What is the net force on the stone in Exercise 81 when it is at the top of its path? What is its instantaneous velocity?

What is its acceleration?

Exercise 81

Suppose that the string in Exercise 80 breaks and the stone slows in its upward motion. Draw a force-vector diagram of the stone when it reaches the top of the path.

Exercise 80

Here the same stone is being accelerated vertically upward.

(a) Draw force vectors to some suitable scale showing the relative forces acting on the stone.

(b) Which is the longer vector, and why?