Answer
(a) k = 199 N/m
(b) The tendon can stretch 0.693 meters without rupturing.
The energy stored in the tendon is 47.8 J.
Work Step by Step
(a) $kx = mg$
$k = \frac{mg}{x} = \frac{(0.250~kg)(9.80~m/s^2)}{0.0123~m}$
$k = 199~N/m$
(b) $kx = 138~N$
$x = \frac{138~N}{199~N/m} = 0.693~m$
The tendon can stretch 0.693 meters without rupturing.
We can find the energy stored in the tendon at that point.
$E = \frac{1}{2}kx^2$
$E = \frac{1}{2}(199~N/m)(0.693~m)^2$
$E = 47.8~J$
The energy stored in the tendon is 47.8 J.
