The elastic energy stored in your tendons can contribute up to 35% of your energy needs when running. sports scientists have studied the change in lenght of the knee extensor tendon in sprinters and nonathletes. they find (on average) that the sprinters' tendons stretch 43mm, while nonatheletes' stretch only 30mm. the spring constant for the tendon is the same for both groups, 33 n/mm. what is the difference in maximum stored energy between the sprinters and the nonathletes?

You have two photos of a person walking. one shows the person at the corner of third and main streets, the other shows the person at the corner of tenth and main streets. there are lampposts at every corner in this town, and the first picture shows it to be 10: 32: 00 exactly. the second picture shows it to be 10: 49: 30. you know three facts: (1) all of the clocks are synchronized; (2) there are exactly 12 equal-sized blocks per kilometer in this town; and (3) the streets that cross main in this area are numbered consecutively, with no interruptions. what is the person’s average speed in kilometers per hour?