Calculating using dv/dt = dh/dt * dv/dh to find dv/dh and then integrating the answer to get a line

hardcoremath

New member
Joined
Mar 14, 2019
Messages
1
Hi,
The object the math question is based around for reference is a cylinder
I know
V=pi*r^2*h
dv/dh = pi*r^2

h = 0.00192882t - 1..32( this line was h = -0.00192882t + 1..32 but the question said to multiply the line by -1)
dh/dt= 0.00192882

r = 4

So therefore if I do the rate of change part right right I should get

0.00192882/16pi = dv/dh

then if I integrate I get

h = 0.000378722921381t + c

Is this correct, I have a feeling I did something wrong because I'm not getting the answer I expected.

I expected a line sloping negatively from the 2nd quadrant through the 1st and then to the 4th
 

Dr.Peterson

Elite Member
Joined
Nov 12, 2017
Messages
3,634
Please state the actual problem you are working on, as requested in our submission guidelines. I have no idea what the line is, or what you are trying to accomplish.
 

HallsofIvy

Elite Member
Joined
Jan 27, 2012
Messages
4,945
"h = 0.00192882t - 1..32( this line was h = -0.00192882t + 1..32 but the question said to multiply the line by -1)". Did you think to wonder WHY? If the first equation is true then the second equation can't be true! You could multiply both sides by -1 so that -h= -0.00192882t+ 1..32. I am still wondering what "1..32" means.
 
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