Civil Engineering - Strength of Materials - Discussion
Discussion Forum : Strength of Materials - Section 5 (Q.No. 20)
20.
A 8 metre long simply supported rectangular beam which carries a distributed load 45 kg/m. experiences a maximum fibre stress 160 kg/cm2. If the moment of inertia of the beam is 640 cm4, the overall depth of the beam is
Discussion:
18 comments Page 1 of 2.
Abinaya Rajendran said:
6 years ago
M/I = sigma/y ..........(1).
Where M = wl^2/8=45*8^2/8.
= 360kg-m.
= 36000kg-cm.
From eqn(1),
36000/640 = 160/y.
Y = 2.844.
Y = d/2 = 2.844.
d = 2*2.844 = 5.68 means 6 cm.
Which is nearer to 10 cm.
So option A is correct.
Where M = wl^2/8=45*8^2/8.
= 360kg-m.
= 36000kg-cm.
From eqn(1),
36000/640 = 160/y.
Y = 2.844.
Y = d/2 = 2.844.
d = 2*2.844 = 5.68 means 6 cm.
Which is nearer to 10 cm.
So option A is correct.
(3)
Ramniwas said:
5 years ago
I = bd^3/12.
Generally b=d/2 take,
640 = d^4/24,
d = 10.
Generally b=d/2 take,
640 = d^4/24,
d = 10.
(1)
Bipin Dhungana said:
6 years ago
Yes, 5.68 cm is the answer.
(1)
Asif Wazir said:
6 years ago
The correct answer is 5.68 cm but as per minimum requirements that is d=l/8, we have to select 10 cm.
(1)
Kewal krishan said:
7 years ago
It's answer is 10cm because depth formula is l/10 to l/8 so we apply the formula.
L/8 = 8000/8 = 1000mm = 10cm.
L/8 = 8000/8 = 1000mm = 10cm.
(1)
Chulbul said:
8 years ago
@Manjunath.
How can b= 8m and d= 10cm?
How can b= 8m and d= 10cm?
Namish Cooper said:
4 years ago
Agree, it's 5.68 cm.
Sathya h d said:
6 years ago
The answer is 5.6 cm, otherwise he has to give the relationship between b and d like b is twice the d, or 2.5 times the d etc, then first find out b, then by using given relationship find D.
NeeL said:
7 years ago
Answer is 6 cm.
Rajeev said:
1 decade ago
Sir please give me explanation of this answer.
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