# Mechanical Engineering - Strength of Materials - Discussion

Discussion Forum : Strength of Materials - Section 2 (Q.No. 6)

6.

The bending moment in the centre of a simply supported beam carrying a uniformly distributed load of

*w*per unit length isDiscussion:

8 comments Page 1 of 1.
Ashwer said:
4 years ago

Can anyone tell me which configuration has Wl/8 bending moment?

Sravan said:
5 years ago

Simply supported beam(point load)then B.M = Wl/4.

Simply supported beam (U.D.L)then B.M = Wl^2/8.

Cantilever beam (point load)then B.M = Wl.

Cantilever beam (U.D.L)then B.M = wl^2/2.

Simply supported beam (U.D.L)then B.M = Wl^2/8.

Cantilever beam (point load)then B.M = Wl.

Cantilever beam (U.D.L)then B.M = wl^2/2.

(3)

Vivek said:
8 years ago

If the centroidal axis and neutral axis of the beam concides, the the stresses at the centre of the beam will be zero.

DEEPAK said:
10 years ago

Firstly calculate shear force i.e. wl/2.

Now calculate the area of shear force diagram you will get bending moment as the shear force diagram is in the form of triangle the area =1/2*base*height i.e 1/2*L/2*WL/2=WL2/8.

Now calculate the area of shear force diagram you will get bending moment as the shear force diagram is in the form of triangle the area =1/2*base*height i.e 1/2*L/2*WL/2=WL2/8.

Vinod rampa said:
1 decade ago

1. Bending moment due to reaction force at one end is = (wl/2)*(l/2).

2. Bending moment due to udl up to l/2 will act at l/4 at with a magnitude of -((w/2)*(l/2))*(l/4) (-ve since clockwise).

So, net B.M. will be the sum of them, which is wl^2/4 - wl^2/8 = wl^2/8.

2. Bending moment due to udl up to l/2 will act at l/4 at with a magnitude of -((w/2)*(l/2))*(l/4) (-ve since clockwise).

So, net B.M. will be the sum of them, which is wl^2/4 - wl^2/8 = wl^2/8.

Yadvendra Kaushik said:
1 decade ago

At both ends reactions will be wl/2 and if we take moment at the centre it comes wl2/8. So answer D is correct.

Akshay said:
1 decade ago

How can moment be zero? you have to consider the support loads at both ends at the centre of the beam.

Akshay said:
1 decade ago

The load is UDL then its point load acts at centre,

Moment at centre is zero.

Moment at centre is zero.

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