Question

I hang a body with a mass of 750 g on a string and the elongation of this one is 1 metre. Calculate its elastic constant. If I hang a body of 3 kg, how much is the elongation now?

Answer 1

Use the hooke's law

$f = k \times x$

K: Elastic constant

X: Elongation

F: Force

1) In this case the force is the mass multiplied by g ( g = 9.8 m/s^2 )

$0.75 \times 9.8 = k \times 1 \\ k = 7.35 \: \frac{n}{m}$

2) In this case the new force is the mass multiplied by g

$3 \times 9.8 = 7.35 \times x \\ \frac{29.4}{7.35} = x \\ x = 4 \: m$