Question

The yield point of a typical solid is about 1%. Suppose you are lying horizontally and two persons are pulling your hands and two persons are pulling your legs along your own length. How much will be the increase in your length if the strain is 1%? Do you think your yield point is 1% or much less than that?

Answer 1

Explanation:  

If the height is H and the height / length increase is h because it pulls then the strain

$=\frac{\hbar}{H}$

If it is 1% then  

$\frac{\hbar}{H}=\frac{1}{100}$

$h=\frac{H}{100}$

If the height H = 180 cm (say) then length increase h = 1.80 cm.

As our body has joints that are weaker than the bones  so That length increase will be at the weakest joint Any joint that has a spacing of 1.80 cm will be very damaging.  The yield (or bearable pain) due to pulling will therefore be much less than 1%.