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:

Answer:
When magnesium reacts with oxygen, it produces light bright enough to blind you temporarily. Magnesium burns so bright because the reaction releases a lot of heat. As a result of this exothermic reaction, magnesium gives two electrons to oxygen, forming powdery magnesium oxide (MgO).
Answer:
It is important because it carries useful energy through your house that you can use for a variety of tasks.
Explanation:
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Answer:
a)KE=878.8 J
b)W=2636.4 J
Explanation:
Given that
mass ,m = 65 kg
Initial speed ,u = 5.2 m/s
a)
We know that kinetic energy KE is given as follows

m=mass
u=velocity
Now by putting the values in the above equation we get

KE=878.8 J
b)
We know that
Work done by all forces = Change in the kinetic energy
The final velocity , v= 2 u = 2 x 5.2 m/s
v= 10.4 m/s

Now by putting the values in the above equation we get

W=2636.4 J
a)KE=878.8 J
b)W=2636.4 J
Answer:

Explanation:
A body has acceleration when there is a change in the velocity vector, either in magnitude or direction. In this case we only have a change in magnitude. The average acceleration represents the speed variation that takes place in a given time interval.
a)

b)
