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akch2002, Engineer
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A flea (mass ≈ 0.5 mg) can jump about 15 cm straight up into

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A flea (mass ≈ 0.5 mg) can jump about 15 cm straight up into the
air. The flea jumps by storing energy in an elastic material known as

a) Suppose you take a cube of resilin 200 µm
on a side, fix one face of it, and then pull with a
known applied force on the opposite face to
stretch the cube, as shown in the diagram. You
then measure the length L of the stretched cube.
The results are shown in the following table:
Applied force (mN) Cube length (µm)
0 200
7 220
14 240
35 300
What is the Youngʼs modulus, E, for resilin?

b) The flea stores energy by stretching a resilin block of unknown
size to 1.5 times its usual length. What mass of resilin does the flea
need to store the energy required for a 15 cm jump? (The density of
resilin is 1.33 g/cm^(3).) Does your answer depend on the individual
dimensions (height, width, and length) of the block?
Kindly upload the diagram as mentioned in the question.
Customer: replied 5 years ago.
Customer: replied 5 years ago.
Re-entering the table mentioned:

Applied force (mN) Cube length (µm)
0 200
7 220
14 240
35 300
(a) Y = stress /strain
Stress = force/area = 7*10^-3/(200*10^-6)^2 = 175000 N/m^2
Strain = l/L = = 20/200= 0.1
Hence, Y = 175000/0.1 = 1.75*10^6 N/m^2

In part(b), stretching constant is required.
Customer: replied 5 years ago.
So in part b, it is not possible to find the mass of the resilin?

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