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Need some help with a area question

  • #1

Homework Statement



The force (in Newtons) that air exerts on a surface is given by the formula
F = 10^5A

Where A is the surface area (in square metres). Suppose that the air supplies 10^6 Newtons of force on a rectangular surface that is 2 metres longer than it is wide. Find the dimensions (to 2 decimal place) of the rectangular surface.

Homework Equations





The Attempt at a Solution



This is my attempt

10^6 = 10^5A
A= 10

10 = LW
10 = (2+w)w
10= 2w +w^2

now i am stuck here..

If anyone knows what to do it would be greatly appreciated if you could help me out, thank you.
 

Answers and Replies

  • #2
danago
Gold Member
1,122
4
Its a quadratic. Could use the quadratic formula
 
  • #3
so what i did was corrent, i just gotta use the quadradic formula and thats it yeh?
 
  • #4
danago
Gold Member
1,122
4
As far as im aware, yes.

For a quadratic like that, the first thing i would do is write it as:

w2+2w-10=0

And see if i can write it in the form (x+a)(x+b)=0. If not, then id probably proceed to use the quadratic formula.
 
  • #5
HallsofIvy
Science Advisor
Homework Helper
41,794
925
Starting from w2+ 2w= 10, completing the square leaps to mind!
 

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