Question

4. (Fig. 18.18). The dimensions of the cross-sectionof a girder, 2.5 m long, are shown in cm in thediagram. Find(i) the volume of the girder,(ii) the weight, if the material weighs 7.8 gmper cm3​

Answer 1

Answer:

I think it is 75

Step-by-step explanation:

but please give brainliest answer

Answer 2

Answer:

Mass, m=14.5kg

Length of the steel wire, l=1.0m

Angular velocity, =2 rev/s=2×2π rad/s=12.56 rad/s

Cross-sectional area of the wire, A=0.065cm

2

=0.065×10

−4

m

2

Let Δl be the elongation of the wire when the mass is at the lowest point of its path.

When the mass is placed at the position of the vertical circle, the total force on the mass is:

F=mg+mω

2

l

=14.5×9.8+14.5×1×(12.56)

2

=2429.53 N

Young's modulus = Stress / Strain

Y=(F/A)/(Δl/l)

Δl=Fl/AY

Youngs modulus for steel =2×10

11

Pa

Δl=2429.53×1/(0.065×10

−4

×2×10

11

) = 1.87×10

−3

m

Hence, the elongation of the wire is 1.87×10

−3

m.