Complete Question:
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 length of the knee extensor tendon in sprinters and nonathletes. They find (on average) that the sprinters' tendons stretch 43 mm , while nonathletes' stretch only 32 mm . The spring constant for the tendon is the same for both groups,
. What is the difference in maximum stored energy between the sprinters and the nonathlethes?
Answer:

Explanation:
Sprinters' tendons stretch, 
Non athletes' stretch, 
Spring constant for the two groups, k = 31 N/mm = 3100 N/m
Maximum Energy stored in the sprinter, 
Maximum energy stored in the non athletes, 
Difference in maximum stored energy between the sprinters and the non-athlethes:

Getting a good night sleep can benefit you in a lot of ways. Also that’s not a question.
Answer:
The heating element of the heater is made up of alloy which has very high resistance so when current flows through the heating element, it becomes too hot and glows red. But the resistance of cord which is usually of copper or aluminum is very low so it does not glow.
Answer:
The Ring of Fire
Explanation:
The ring of fire is also called the Circum-Pacific Belt, it is a path along the pacific ocean consisting of active volcanoes and frequent earthquakes.
It has a length of approximately 40,000 kilometers. It lies on the edge of tectonic plates where the in-earth vibrations and geothermal energies are prone to erupt out.
Ring of fire inhibits about 75% o the earth's volcanoes and 95% of earthquakes occur in this region.
I would say A Because it weighs more than the water