Question

When the load on a wire is slowly increased from `3kgwt` to `5 kg wt`, the elongation increases from `0.61` to `1.02 mm`. The work done during the extension of wire is
A. `16xx10^-3J`
B. `8xx10^-2J`
C. `20xx10^-2J`
D. `11xx10^-3J`

Answer 1

Correct Answer - A
Work done in stretching the wire through `0.61mm` under the load of `3kg wt`.
`W=(1)/(2)` streching`xx`extension
`=(1)/(2)xx3xx9.8xx0.61xx10^-3`
`=8.967xx10^-3J` ltbr. Work done in stretching the wire through `1.02`mm under the load of `5kg` wt
`W_2=(1)/(2)xx3xx9.8xx1.02xx10^-3`
`=34.99xx10^-3J`
Hence the work done in stretching the wire from `0.61mm` to `1.02mm`
`triangleW=W_2-W_1=(24.99-8.961)xx10^-3`
`=16xx10^-3J`