# Mechanical Engineering - Strength of Materials - Discussion

Discussion Forum : Strength of Materials - Section 1 (Q.No. 42)

42.

The rectangular beam '

*A*' has length*l*, width*b*and depth*d*. Another beam '*B*' has the same length and depth but width is double that of '*A*'. The elastic strength of beam '*B*' will be __________ as compared to beam*A*.Discussion:

9 comments Page 1 of 1.
Saiteja said:
7 months ago

E=stress/strains, stress = F/A.

As in the problem said length and depth are the same but worth is different.

E1 = F/b1 * d1,

E2 = F/b2 * d2,d1 = d2,

E1/E2 = 1/2.

As in the problem said length and depth are the same but worth is different.

E1 = F/b1 * d1,

E2 = F/b2 * d2,d1 = d2,

E1/E2 = 1/2.

(1)

Jehan said:
7 years ago

Strength is directly proportional to depth sq x width hence if depth is const. Width will vary. Thus exist linear rship.

Y K Sinha said:
7 years ago

Yes. The answer should be half.

Saif said:
7 years ago

Yes, Agree @Madhu.

The answer should be half.

The answer should be half.

(1)

Nagar said:
8 years ago

A yield strength or yield point is the material property defined as the stress at which a material begins to deform plastically. Prior to the yield point, the material will deform elastically and will return to its original shape when the applied stress is removed.

Madhu said:
8 years ago

My = S * σy.

S = I / y.

So, I think the answer will be half.

S = I / y.

So, I think the answer will be half.

Siddu said:
8 years ago

Plese, give a clear solution.

(1)

SAURABH said:
9 years ago

Elastic strength directly measure by the term of section modulus.

Than section modulus Z(A) = I(a)/y(a).

Z(A) = (BD^3/12)/(D/2).

= BD^2/6 ------------ equation (1).

Where B is breath and D is depth of rectangular section (A).

According to question B(a) = 2*B(b) in case of Rectangular Section.

Z(B) = (2B*D^3/12)/(D/2).

= BD^2/3.

Then, Z(A)/Z(B) = (BD^2/6)/(BD^2/3).

Z(A)/Z(B) = 1/2.

Z(B) = 2 Z(A).

Than section modulus Z(A) = I(a)/y(a).

Z(A) = (BD^3/12)/(D/2).

= BD^2/6 ------------ equation (1).

Where B is breath and D is depth of rectangular section (A).

According to question B(a) = 2*B(b) in case of Rectangular Section.

Z(B) = (2B*D^3/12)/(D/2).

= BD^2/3.

Then, Z(A)/Z(B) = (BD^2/6)/(BD^2/3).

Z(A)/Z(B) = 1/2.

Z(B) = 2 Z(A).

(1)

Manish said:
10 years ago

Elastic strength is directly proportional to section modulus. Z(B) = 2 Z(A)..

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