Question

The elastic energy stored in your tendons can contribute up to 35% of your energy needs when running. Sports scientists find that (on average) the knee extensor tendons in sprinters stretch 41 mm while those of nonathletes stretch only 33 mm. The spring constant of the tendon is the same for both groups, 33 N/mm. What is the difference in maximum stored energy be-tween the sprinters and the nonathletes?

Answer 1

The equation we want to use for this is P=1/2kx^2, with P being stored energy, K being spring constant, and x being displacement. For sprinters, the equation would be


1/2(33)(41)^2= 27736.5

And for non athletes:

1/2(33)(33)^2= 17968.5

Subtract the two and you get: 9768 J of energy