question_answer 4)

An adge of a variable cube is increasing at the rate of 3 cm/s. How fast is the volume of the increasing when the edge is 10 cm long ? 

Answer:

Let a is the edge and V be the volume of the cube.       Given       Now V = a3               [By (1)]       = 9a2             Volume of cube is increasing at the rate 900 cm3/s.