Question

Sand is being poured at a rate of 2 m^3/second onto a conical pile of sand that is initially 2 meters in height with a base diameter of 6 meters. How fast is the height of the pile increasing at the moment when the pile of sand is 4 meters in height?

Answer 1

dv/dt= 2

dh/dt=?

v= 1/3 Pi r^2 h

dv= 1/3 Pi r^2 dh

Answer 2

2=1/3 Pi (3)^2 dh

use algebra to find dh