Question

an elastic cord 61 cm long when a weight of 75N hangs from it, but 85cm when a weight of 210N hangs from it. what is the spring constant of the cord

Answer 1

Answer:

560 N/m

Explanation:

F = kx

75 N = k (0.61 m − L)

210 N = k (0.85 m − L)

Divide the equations:

2.8 = (0.85 − L) / (0.61 − L)

2.8 (0.61 − L) = 0.85 − L

1.708 − 2.8L = 0.85 − L

0.858 = 1.8L

L = 0.477

Plug into either equation and find k.

75 = k (0.61 − 0.477)

k = 562.5

Rounded to two significant figures, k = 560 N/m.