Mechanical Engineering - Strength of Materials - Discussion

Discussion Forum : Strength of Materials - Section 2 (Q.No. 32)
32.
The rectangular beam 'A' has length l, width b and depth d. Another beam 'B' has the same length and width but depth is double that of 'A'. The elastic strength of beam B will be __________ as compared to beam A.
same
double
four times
six times
Answer: Option
Explanation:
No answer description is available. Let's discuss.
Discussion:
11 comments Page 1 of 2.

Kothai Arjunan said:   5 years ago
Z= I/y.
for A- l.b.d.
for B-l,b,2d.

Using I = bd^3/12 y= d/2.
Find (B/A)'s Moment of inertia by replacing d = 2d for Beam B.
(2)

Rupok Kumar Saha said:   6 years ago
Is it same section modulus and elastic Strength? Please tell me.

Sagar said:   6 years ago
Agree @Yallu.

It will be Za/Zb=1/4.

Sachin said:   6 years ago
I thinking 2 times.
(1)

Vikas said:   7 years ago
Does elastic section modulus refer as elastic strength?

Yallus said:   8 years ago
Z = I/y.
I = bd^3/12.
Y = d/2.
Za = bd^2/6.

But in Zb depth is double so d = 2d.

Zb = (b*(2d)^3/12)/d/2.
Zb = 2bd^2/3,
Za/Zb = 4,

Venkat said:   9 years ago
Answer c is correct.

z = b.h^2/12 ; h = 2h(supstitute it).

z = b.(2h)^2/12;

z = 4(b.h^2/12);

Then finally, z = 4(z).

Manjeet Singh said:   9 years ago
Elastic strength directly proportional to section modulus. So the answer is B.
(1)

Ansh said:   9 years ago
It would be 8 times.

Anonymous said:   9 years ago
Elastic section modulus for rectangular beam is S = b*h^2/6.


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