At what rate must the string be let out when the length of the string already let out is 50 meters?

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?