A spring $40 \,mm$ long is stretched by the application of a force. If $10 \,N$ force required to stretch the spring through $1 \,mm$, then work done in stretching the spring through $40\, mm$ is ............. $\mathrm{J}$
A spring $40 \,mm$ long is stretched by the application of a force. If $10 \,N$ force required to stretch the spring through $1 \,mm$, then work done in stretching the spring through $40\, mm$ is ............. $\mathrm{J}$
$84$
$68$
$23$
$8$
A spring $40 \,mm$ long is stretched by the application of a force. If $10 \,N$ force required to stretch the spring through $1 \,mm$, then work done in stretching the spring through $40\, mm$ is ............. $\mathrm{J}$
Here $k = \frac{F}{x} = \frac{{10}}{{1 \times {{10}^{ - 3}}}} = {10^4}\,N/m$
$W = \frac{1}{2}k{x^2} = \frac{1}{2} \times {10^4} \times {(40 \times {10^{ - 3}})^2} = 8\,J$
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