00:01
Okay, here we have a cylindrical cell with radius r equals 5 cm, height equals 40 centimeter, and the thickness of the shell is given as 0 .9 centimeter.
00:13
So this basically represents the dr quantity.
00:17
So first we will replace the volume of a cylinder, which is given by v equals pi r squared, h.
00:25
Here we know that h remains the constant only the radius is changing.
00:31
Only when the radius is changing, we know that we are getting a thickness of the shell.
00:37
So let's differentiate this volume with respect to radius.
00:41
And so we can write down this as a dv by d r and this equals this pi and h are constant.
00:48
So i can put them as in front without differentiating.
00:52
And then we have to differentiate only r squared with respect to r which gives two r when we use the power root.
01:00
So let's simplify this.
01:01
So this equals 2 pi h times r.
01:06
This is dv by d r.
01:09
Now let's multiply both sides with this quantity that is d r...