A wee little problem (1 Viewer)

[lacklustre]

Hi guys,

Atm I am a little confused with rates of change.

Attached are a couple of questions (q6 and q7) which I have no idea.

Ta.​

 

[solomarc20]

U always need 2 use the chain rule 4 these questions.

In q7, u've got dV/dt, and dV/dh (differentiate V=300h^2)

dh/dt = (dh/dV)x(dV/dt)

get an expression for h, and then subst h=20 in2 the expression 4 h