The Achilles tendon connects the muscles in your calf to the back of your foot. When you are sprinting, your Achilles tendon alternately stretches, as you bring your weight down onto your forward foot, and contracts to push you off the ground. A 70 kg runner has an Achilles tendon that is 15 cm long with a typical 1.1×10−4m2 area.
A. By how much will the runner's Achilles tendon stretch if theforce on it is 8.0 times his weight?
B. What fraction of the tendon's length does this correspond?

Explanation:

Given:

Mass, M = 70 kg

Area, A = 1.1 × 10^-4 m^2

Achilles tendon length, l = 15 cm

= 0.15 m

Young modulus for tendon, E = 0.15 × 10^10 N/m^2

Young modulus, E = tensile stress/tensile strain

But,

Stress = force/area

Strain = extension/length

A.

Force = 8 × N

N = m × g

= 70 × 9.8 × 8

= 5488 N

Extension = (force × length)/(area × yound modulus)

= (5488 × 0.15)/(1.1 × 10^-4 × 0.15 × 10^10)

= 4.989 mm

= 0.005 m

B.

Fraction of length, x = extension/original length

= 0.005/0.15

= 0.033

= 3.3 %

jupiter is the largest planet in our solar system, having a mass and radius that are respectively, 318 and 11.2 times that of earth. suppose that an object falls from rest near the surface of each planet and that the acceleration due to gravity remains constant during the fall. each object falls the same distance before striking the ground. determine the ratio of the time of fall on jupiter to that on earth.

tbh i don't know the answer for this question