Minimize Cost: Find Dimensions & Total Cost of Box w/ 16000cm^3 Volume

  • Context: High School 
  • Thread starter Thread starter Spectre32
  • Start date Start date
  • Tags Tags
    Box Dimensions Volume
Click For Summary

Discussion Overview

The discussion revolves around finding the dimensions and total cost of a closed box with a square base that must have a volume of 16000 cm³. Participants explore the implications of cost associated with different surfaces of the box and the mathematical approach to minimize this cost.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant presents the problem of a closed box with a square base and a specified volume, seeking help to find dimensions that minimize cost.
  • There is confusion regarding the cost per square centimeter for the top and bottom versus the sides, with clarifications made by participants.
  • A participant outlines the volume and cost equations, suggesting that one can eliminate a variable to express cost in terms of two variables for minimization.
  • Another participant points out the initial misunderstanding of the box's shape, emphasizing that it should be treated as a square prism.
  • Concerns are raised about whether a solution exists if the box were not a square prism, questioning the sufficiency of the provided data.
  • One participant suggests that minimizing the areas of the top and bottom will likely lead to minimizing costs, although they acknowledge uncertainty in their reasoning.
  • A later reply introduces a broader perspective on optimization problems, mentioning the sphere as a shape with maximal volume per unit surface area, but questions the practical aspects of such a shape for this problem.

Areas of Agreement / Disagreement

Participants express uncertainty regarding the implications of the box's shape on the solution and whether the problem can be solved without additional data. There is no consensus on the best approach to minimize cost or the necessity of the box being a square prism.

Contextual Notes

Participants note the potential complexity of the problem, including the need for calculus techniques and the implications of different shapes on cost minimization. There are unresolved assumptions about the box's dimensions and cost structure.

Spectre32
Messages
136
Reaction score
0
Ok my teacher was going over this today, but i have no idea how to solve this.

A Closed box with a square base is to have a volume of 16000cm^3. The top and bottme cost 3 persq/cm. while the top is 1.50 pr sq/cm Find the demison of the box that will lead to the total minium total cost. WHat is the total cost.
 
Physics news on Phys.org
So does the top cost 3/cm^2 or 1.5/cm^2?

cookiemonster
 
Whoops. my bad. THe top and bottem are $3per sq/cm and the sides are $1.5 per sq/cm
 
Okay. The box is a rectangular prism. It has a base of dimensions length (l) and width (w). It also has height (h). Its volume is defined by

V = l*w*h

which is required to be 16000cm^3, so

lwh = 16000.

Additionally, the cost of the box is given by

C = $1.5*2(lh + wh) + $3*2(lw)

Using the equation for volume you can eliminate one of the variables, giving you the cost in terms of only 2 variables. You'll have to minimize this function using techniques you learned in class.

Why don't you give it a shot and post what you get?

cookiemonster
 
I thought the box was a square prism ("A Closed box with a square base")...
 
So it is. 3 mistakes in 1 day. Go me.

It's easy to fix. Just let l = w and minimize the remaining variable.

cookiemonster
 
Is there actually an answer to the question if the box was not a square prism, and no other data was supplied? Can't see how myself. :smile:
 
I don't think it matters either way. The top and bottom contribute most to the cost, so minimizing those areas will likely minimize the cost as well. It just makes the math a bit more difficult.

Then again, I haven't run the numbers, so I could be (and considering the day, probably am) wrong.

cookiemonster
 
You have to at least state what kind of aperture you want on the 'box'. The (smooth) surface with maximal volume per unit of surface area is the sphere; but where do you put stuff in? These problems are (often) solvable with calculus of variations (probably) subject to the smoothness constraints etc.
 

Similar threads

  • · Replies 1 ·
Replies
1
Views
3K
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
4K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 15 ·
Replies
15
Views
4K
  • · Replies 7 ·
Replies
7
Views
4K
  • · Replies 11 ·
Replies
11
Views
7K
  • · Replies 2 ·
Replies
2
Views
3K
  • · Replies 1 ·
Replies
1
Views
2K