A rock of mass 200g is attached to a 0.75m long string and swung in a vertical plane. A) what is the speed that the rock must travel so that its weight at the top of the swing is 0? B) what is the tension in teh string at the bottom of the swing? C) if the rock is now moved to a horizontal swinging position, what is the angle of the string to the horizontal? Here is what i could do: I drew a vertical circle with 2 positions a and b. A is at the top and B is at the bottom. so at A the F_g is down and T is up. at B,T is down and F_g is up. Right? then what?