When load on a wire is increased from 4 kgf to 6 kgf, the elongation increases from 0.71 mm to 1.12 mm. Find the workdone during the extension of the wire.

Answer

`19.012 xx 10^(-3) J`

Explanation

case (i) `F_1 =4 kgf = 4xx 9.8 N,`
`Delta l_1 = 0.71 mm = 0.71 xx 10^(-3) m`
workdone `W_1 = (1)/(2) F_1 xx Delta l_1 = (1)/(2) xx(4xx9.8)`
`xx(0.71 xx 10^(-3))`
` = 13.916 xx 10^(-3) J`
case (ii) `F_2 = 6kgf = 6xx 9.8 N,`
`Delta l_2 = 1.12xx10^(-3) m`
workdone, `W_2 = (1)/(2) xx F_2xx Delta l_2`
` = (1)/(2) xx (6xx9.8)xx(1.12xx 10^(-3))`
` =32.928 xx 10^(-3) j` Therefore workdone in stretching the wire from 0.71 mm to 1.12 mm is `Delta w_1 = w_2 - w_1 =(32.928 - 13.916)xx 10^(-3)`
` = 19.012 xx 10^(-3) j`