Anthropology homework help. At what rate must the string be let out when the length of the string already let out is 50 meters? (Ans: 2.4 m/sec) 8. An icicle is in the shape of a right circular cone. At a certain point in time the height is 15cm 1 and is increasing at the rate of 1cm/hr; the radius is 2cm and decreasing at the rate 10 cm/hr. Is 1 the volume (V = 3 r2 h) increasing or decreasing at this instant? At what rate?