The elastic energy stored in your tendons can contribute up to 35{\ m \\\\%} of

Question

The elastic energy stored in your tendons can contribute up to 35{ m \%} of your energy needs when running. Sports scientists have studied the change in length of the knee extensor tendon in sprinters and nonathletes. They find (on average) that the sprinters' tendons stretch 43mm , while nonathletes' stretch only 31mm .

The spring constant for the tendon is the same for both groups, 33N/mm . What is the difference in maximum stored energy between the sprinters and the nonathletes?The spring constant for the tendon is the same for both groups, 33N/mm . What is the difference in maximum stored energy between the sprinters and the nonathletes?

Explanation / Answer

spring constant K = 33 N/mm = 33000 N/m

Potential energy ( P.E ) = (1/2) * K* x2

For Sprinters the maximum stored energy is

P.Esp = (1/2) * 33000*(0.043)2                           ( x = 0.043 m)

= 30.508 J

For non-athletes

P.E na = (1/2)*33000*( 0.031)2

= 15.856 J

The difference in maximum energy stored between sprinters and non-athelete = 30.508 - 15.856

                                                                                                                 = 14.65 J

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