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Help!

I need help with this question: “ your company is manufacturing requiring surface coatings. As part of your training, you have been asked to investigate if a cylindrical product has the least surface area for the volume it contains. The volume is currently 200cm^3 with height of 65mm and radius of 34mm. Can you improve on this” I need this due in this Friday. I have done some workings out.

Using differentiation:
H=65
R=34
H=200/πr^2
A=2πrh 2πr^2
A= 400πr/πr^2 2πr^2
A=400/r 2πr^2

What do I do next? Please send your workings out with an answer

(edited 5 years ago)

Reply 1

mqb2766

Original post by Rohit94994

I need help with this question: “ your company is manufacturing requiring surface coatings. As part of your training, you have been asked to investigate if a cylindrical product has the least surface area for the volume it contains. The volume is currently 200cm^3 with height of 65mm and radius of 34mm. Can you improve on this” I need this due in this Friday. I have done some workings out

H=65
R=34
H=200/πr^2
A=2πrh+2πr^2
A= 400πr/πr^2 +2πr^2
A=400/r +2πr^2

I really don't know what you're trying to work out in the above? Generally, a bit of explanation helps.
Have you checked whether the stated cylinder has a volume of 200cm^3? If you're asked to improve on something, first make sure you understand the basic product.
If you're restricted to cylinders, depending on your level, you could do some differentiation or just change the radius (height) slightly in each direction and see what happens. Depends on what you're current level is.

Reply 2

Rohit94994

You need to use differentiation to find the minimum surface area. Would you show your workings out for this please??

Reply 3

mqb2766

Original post by Rohit94994

You need to use differentiation to find the minimum surface area. Would you show your workings out for this please??

Are you A-level, gcse or ... ?

Reply 4

Rohit94994

A level. Please can you send your workings out with answer?

Reply 5

mqb2766

Original post by Rohit94994

A level. Please can you send your workings out with answer?

No. I'm not doing your work for you.
You've got an expression for the area in terms of the radius. What do you think happens now.

Idk

Original post by Rohit94994

Idk

The "Using differentiation" in the question gives a hint.

Reply 8

Rohit94994

I used differentiation but Idk where Togo next

Reply 9

mqb2766

Original post by Rohit94994

I used differentiation but Idk where Togo next

Can you show your working?

Reply 10

Rohit94994

H=65
R=34
H=200/πr^2
A=2πrh 2πr^2
A= 400πr/πr^2 2πr^2
A=400/r 2πr^2

Reply 11

mqb2766

Original post by Rohit94994

H=65
R=34
H=200/πr^2
A=2πrh 2πr^2
A= 400πr/πr^2 2πr^2
A=400/r 2πr^2

You said you used differentiation, but there is no differentation there. You have a formula for Area in terms of Radius. You want to find the minimum value (where the derivative equals zero), its a straightforward application of calculus?

Reply 12

Rohit94994

Yes it involves calculus

Reply 13

mqb2766

Original post by Rohit94994

Yes it involves calculus

Try differentiating the Area expression, setting it equal to zero and solving.

You had a similar question a couple of months ago:
https://www.thestudentroom.co.uk/showthread.php?p=80790986
You'll only learn if you try and do it yourself, even if you make a mistake.