The maximum compressive stress at the top of a beam is 1600 kg/cm^{2} and the corresponding tensile stress at its bottom is 400 kg/cm^{2} . If the depth of the beam is 10 cm, the neutral axis from the top, is

[A].

2 cm

[B].

4 cm

[C].

6 cm

[D].

8 cm

[E].

10 cm.

Answer: Option D

Explanation:

No answer description available for this question.

Here, n/d = m x Compressive / m x Comp. + tensile.

M = modular ratio, not given you can take it 18 approx.
Solving will give 9.8 cm almost 8.

Spsg said:
(Aug 8, 2017)

E/R is same so equate bending stress/distance from nutral axis for both tensile and compressive.

Sudinbanerjee said:
(Aug 13, 2017)

Your explanation is absolutely correct, Thanks @Ganesh.

Satya said:
(May 25, 2018)

Thank you @Ganesh.

Reddy said:
(Jul 29, 2018)

Thank you @Ganesh.

Bittu said:
(Aug 5, 2018)

Thanks @Ganish.

Munni said:
(Dec 25, 2018)

Max tensile stress/max. Compressive stress=m (d-h/h) , considering m which is the modular ratio=1 we get 400/1600=1 (10-h/h), by solving we get h=8cm.

Pawan said:
(Mar 13, 2019)

Thank you very much @Ganesh.

Protul said:
(Jun 26, 2019)

Thanks all for explaining it.

Rabin Das said:
(Feb 5, 2020)

Thanks @Ganesh.

Raj Keshri said:
(Sep 12, 2020)

Since we know that, sigma/y in bending equation is equal for both compressive and tensile stresses, So,
Let, a distance of neutral axis from the top be x.
Therefore the distance of the bottom layer from the neutral axis is 10-x.
Therefore; (Compressive stress/x) = (tensile stress/10-x).

Srikanta said:
(Nov 18, 2020)

1600/x = 400/(10-x).
5x = 40.
X = 8 cm.
Where x = Depth of neutral axis from top.

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