A right circular conical funnel has total height 30 cm and top radius 10 cm

MATHEMATICS · Multi-part · CBSE · Mathematics · Applications of Derivatives · Applications of Derivatives

Problem

A right circular conical funnel has total height 30 cm and top radius 10 cm. Initially, the funnel is full of water. Water drains through a small hole at the tip at a constant rate of 15 cm3^{3}/s. Let h(t)h(t) be the water depth (in centimeters) at time tt seconds. (a) Obtain an equation expressing the volume of water in the funnel as a function of hh. (b) Find the instantaneous rate of change dhdt\dfrac{dh}{dt} when the water depth is 12 cm. State the answer with units. (c) Determine how fast the radius of the water surface is changing, drdt\dfrac{dr}{dt}, at the same instant.

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