Im stuck on this question can someone please walk me through it.
An underground storage tank is being filled with liquid as shown in the diagram. Initially the tank is
empty. At time t hours after filling begins, the volume of liquid is V m
3 and the depth of liquid is h m.
It is given that V = 4/3h
3The liquid is poured in at a rate of 20m
3 per hour, but owing to leakage, liquid is lost at a rate
proportional to h
2.
When h = 1, dh/dt = 4.95.
(i) Show that h satisfies the differential equation
dh/dt = 5/h2 - 1/20
(ii) Verify that 20h
2/(100 - h
2) = 20 + 2000/((10 - h)(10 + h))
(iii) Hence solve the differential equation in part (i), obtaining an expression for t in terms of h.
This is CIE, 9709/03 (mathematics paper 3), October November 2008, question 8. I've attached the paper
Any help would be much appreciated.