Q.

A spring of young's modulus 2 ×1011 pa is suspended vertically and subjected to a load of 5 kg and elongation is 2 mm. when the load is doubled-match the following (g = 9.8 m/s2)
      Section - A                         Section - B
a) Elongating force                  e) 4 mm 

b) Stress                                    f) Unchanged 

c) Elongation                            g) 98 N 

d) Young's modulus                h) Doubled 

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a

 a–g; b–h; c–e; d–f 

b

a–e; b–f; c–g; d–h 

c

a–h; b–g; c–f; d–e 

d

a–f; b–e;  c–g; d–h

answer is B.

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Detailed Solution

The formula for the elongating force (F) in a spring is given by Hooke's Law:

F = k × ΔL

where k is the spring constant, and ΔL is the change in length. The stress (σ) is given by:

σ = FA

where A is the cross-sectional area of the spring. The Young's modulus (Y) can be calculated as:

Y = σε

where ε is the strain, which is the ratio of the change in length to the original length.

Given that the Young's modulus of the spring is 2×1011 Pa, the original elongation is 2 mm, and the original load is 5 kg (i.e., 5×9.8N), we can calculate the original values for the other quantities as follows:

F=mg

Now, when the load is doubled, the new elongation is 4 mm, and the new force is 2× 5×9.8 N = 98 N. 

Stress,

S=2mgA=2(S)

which is doubled.

Strain,

strain=stressY

L=mgLAY

Lm

Lf=2L

Hence the correct answer is  a–g; b–h; c–e; d–f .

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A spring of young's modulus 2 ×1011 pa is suspended vertically and subjected to a load of 5 kg and elongation is 2 mm. when the load is doubled-match the following (g = 9.8 m/s2)      Section - A                         Section - Ba) Elongating force                  e) 4 mm b) Stress                                    f) Unchanged c) Elongation                            g) 98 N d) Young's modulus                h) Doubled