Question

Many caterpillars construct cocoons from silk, one of the strongest naturally occurring materials known. Each thread is typically 2.0 μm in diameter, and the silk has a Young's modulus of 4.0 × 10 9 N / m 2 .

a)Assuming that there is no appreciable space between the parallel strands, how many strands N would be needed to make a rope 9.0 m long that would stretch only 1.02 cm when supporting a pair of 91-kg mountain climbers?

N=_____strands

b) Again assuming that there is no appreciable space between the parallel strands, what would be the diameter d of the rope?

d=____cm

Answer 1

a)

FI YAN

91 * 9.8 * 9 N*7 *(10-6)2 * 1.02 * 10-2

N = 6.26 * 107

b)

6.26 * 101 клж (10-)2 = п R-

R=0.79 cm

D = 1.58 cm