A $20-$cm$-$long rod with a diameter of $0\mathrm{.}28$ cm is loaded with a $5000$ N weight. Determine the engineering strain at this load when the diameter decreases to $0\mathrm{.}24$ cm$.$ Assume that the necking point has not been reached.$($Round the final answer to four decimal places.$)$

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The engineering strain on the rod when its thickness changes from$0\mathrm{.}28$ cm to $0\mathrm{.}24$ cm on being loaded with a weight of$5000$ N is