Civil Engineering - Strength of Materials - Discussion


A rectangular bar of width b and height h is being used as a cantilever. The loading is in a plane parallel to the side b. The section modulus is

[D]. none of these.

Answer: Option C


No answer description available for this question.

Mukesh Yadav said: (Apr 23, 2013)  
Section modulus = I/Y(max).

Then I = (b^3*h)/12.

And y = b/2.

Then z = (b^2*h)/6.

Mahesh said: (May 21, 2013)  
Section modulus = I/y(max).

Here the load is parallel to the width b so,
I = (b^3*h)/12.

And y = b/2.

Then z = (b^2*h)/6.

C.Mallireddy said: (Jul 16, 2013)  
Section modulus = I/Y (this is max).

Moment of inertia (I) = (d*b^3)/12.

= (h*b^3)/12.

In this problem width = b.

Depth d = h.

And y = b/2.

:- Z= ( (h*b^3)/12)/(b/2).

Z = (h*b^2)/6.

Prem Kumar Meena said: (Sep 1, 2013)  
Z = I/Y(max.) I = bd^3/12 ;

y(max.) = d/2 load is parallel to side b then b=h and d=b ;

Z = hb^3/12/b/2 ;

Z = hb^2/6.

Deepak Singh said: (Oct 11, 2014)  
We know,

Z = I/Y [where, y=y(max)].
But, I = db^3/12.
y = b/2.

Now, Z = 2db^3/12d,
= db^2/6 [A/C to question d=h],
Z = hb^2/6.

Raj said: (Dec 10, 2014)  
Can somebody explain me "plane parallel to side b"?

Josh said: (Jan 3, 2015)  
Its like load is normal to height h which means parallel to b.

Ithi said: (Jan 30, 2015)  
(hb^3)% (0.5b) = (hb^2%6).

Rima said: (Jun 23, 2015)  
Section modulus = I/Ymax.

Here I = h*b^3/12.

And Ymax = b/2, then section modulus= (h*b^3/12)/(b/2) = h*b^2/6.

Gyan Prakash Tiwari said: (Jul 6, 2015)  
If b is width and h is height then section of modulus.

z = I/Y ; I = hb^3/12 and y = b/2 then.

z = (hb^3/12)/(b/2).

Then z = (b^2/6) is answer. Because the load is in a plane to the side b.

Ooha said: (Jul 15, 2015)  
We are using different methods but same concept. So your process is correct no comment.

Rehan Rufead said: (Jul 22, 2016)  
Section modulus for the rectangular section is 1/6 bd^2. ie I/y.
I = bd^3/12.
Y = d/2 bd^2/6.

Then, how the answer is option C.

Devendranaik said: (Sep 2, 2016)  
Section modules (z) =I/Y.


Y = b/2.

Therefore = Z = I/Y = B^2h/6.

Aftershock said: (Oct 20, 2016)  
It says parallel to the plan b, that means.

I = bh^3/12.
y = b/2,
Hence Z= b^2h/6.

Ghanshyam said: (Nov 20, 2016)  
Please explain that what is y and how y = b/2?
And how calculation is z = {(h*b^3/12)/(b/2).

Ghanshyam said: (Nov 20, 2016)  
What is section module?

Satyendra said: (Jan 7, 2017)  
Section modulus is a geometric property for a given cross-section used in the design of beams or flexural members.

Ummar Basha said: (May 16, 2017)  
Here, bd^3/12.

Because I xx of rectangular section.

Rpr said: (Aug 10, 2017)  
Z= (Moment of Inertia )/(Depth of NA).
= (bh3/12)/(h/2)=bh2/6.

Samir Sahoo said: (Dec 16, 2017)  
Thank you for the explanation.

Priya said: (Jan 2, 2018)  
Please explain that when section modulus bh2/6?

Aaron said: (Jan 14, 2018)  
How y=b/2?

Riyas said: (Jan 25, 2018)  
Section modulus is the ratio of MOI of N.A & Distance from NA from the extreme stressed fibre.
Here NA plays the main role. The load applied in the face of Length x depth. This face elongated & opposite face compressed. So, NA will lie in between this. That means NA will pass perpendicular to width. so MOI will be b^3.d/12.

Distance from n.a. to extreme stressed fibre is b/2.

Jeldi said: (Jan 29, 2018)  
In general terms b= width and d or h = depth or height respectively. When loading is applied we consider bd^3/12 (hear loading is parallel to depth) and y=d/2.

Hear in this problem,

Parallel to width is asked making it shifting terms from width as depth (assume that u have rotated your beam)
So hear instead of bd^3 /12 and y=d/2.
V get db^3/12 and y= b/2.
Making Z=I/Y as db^2/6.

Star Guy said: (Feb 4, 2018)  
Thanks for explaining in an uderstandable manner @Riyas.

James said: (Aug 13, 2018)  
The correct Answer must be (bd3/12)/(d/2) which means bd2/6.

Subrata Pal said: (Aug 26, 2018)  
Thanks for all the given explanation.

Loki said: (Sep 4, 2018)  
Loading is parallel to side b then neural axis is perpendicular to side b, I about n.a ( n.a is the axis parallel to bending direction by right-hand thumb rule ) when the plane of loading is symmetry.

Avi said: (Jan 3, 2019)  
I think, option B is correct.

Elias said: (Apr 3, 2019)  
Thank all.

Akshay Malviya said: (Jun 20, 2019)  
Here in the question, it is written that load is in the "plane parallel to side b". Neutral axis should be parallel to b and the correct answer should be option B.

Pradeep Karsh said: (Aug 30, 2019)  
Thaks to all.

Sai Chandu said: (Apr 24, 2020)  
@Mukesh Yada.

Please explain How y=b/2?

Anantharami Reddy said: (Apr 29, 2020)  
Option B is correct.

Jothi said: (May 4, 2020)  
Section Modulus Z=I/ymax in general I= bd3/12 in this problem d=b ,b=h.

The loading is in a plane parallel to the side b. ymax= b/2, Z= hb3/12/b/2 =b2h/6.

Venkatesh said: (Dec 2, 2020)  
Option B is the correct answer.

Poluri Naresh said: (Dec 12, 2020)  
Options B is the correct answer.

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