Young's Modulus - 10 points correct procedure!?

Question

Resilin is a rubber-like protein that helps insects to fly more efficiently. The resilin, attached from the wing to the body, is relaxed when the wing is down and is extended when the wing is up. As the wing is brought up, some elastic energy is stored in the resilin. The wing is then brought down with little muscular energy, since the potential energy in the resilin is converted back into kinetic energy. Resilin has a Young's modulus of 1.7x106 N/m2. If the insect wing has resilin with a relaxed length of 2.0 cm and with a cross-sectional area of 1.0 mm2, find the magnitude of the force (in N) that the wing must exert to extend the resilin to 4.0 cm?

Answer 1

Ok, let's just work with the definition of Young modulus :

Y = (F/A) / (dL / L)

dL = change of lenght

L = initial lenght

A = surface

1.7*10^6 = (F / A)( 4-2 / 2)

A = 1*10^-6

dL = 2*10^-2

Lo = 2*10^-2

1.7*10^6 = F / 10^-6

F = 1.7 Newtons

Note : I am considering that the Young modulus is : 1.7*10^6 ok.