011-40705070  or  
Call me
Download our Mobile App
Select Board & Class
  • Select Board
  • Select Class
Bharati S from Dr.M.S.Udayamurthy School of Excelence (C.B.S.E), Namakkal,, asked a question
Subject: Math , asked on 14/10/09

If the diameter of the cross section of the wire is decreased by 5%,how much %will the length be increased so that the volume remains the same

Certified by MeritNation Expert

CERTIFIED ANSWER

Suresh Anand From D.a.v. Boys Senior Secondary School, added an answer, on 6/2/12
386 helpful votes in Math

 V = pi.h.r^2 (cylinder)

When diameter is decreased by 5%, radius also is decreased by 5%. So new radius is 19r/20.

So V becomes pi.h.(19r/20)^2 = pi.h.(361r^2)/400.

But you want to maintain the volume at a constant, so h is to be multiplied by 400/361 to keep it constant.

So length is to be incresed by 400/361 - 1 = 39/361 times, i.e. 39 x 100/361 = 10.8033 %

This conversation is already closed by Expert

  • Was this answer helpful?
  • 17
94% users found this answer helpful.
View More
Bharati S From Dr.m.s.udayamurthy School Of Excelence (c.b.s.e), Namakkal,, added an answer, on 18/10/09
3 unhelpful votes in Math

thankyou for your reply.....what are you studying?

  • Was this answer helpful?
  • -3
No user found this answer helpful.