physics question

Question

An elastic band stretches from 0.1m to 0.15m when a mass of 225g is suspended from the elastic band. What is the spring constant of the elastic band?

Answer 1

Hi Sammie

The Spring Constant - k exerts a force equal to -kx. So for the elastic band that is stretched by 0.15 - 0.1 = 0.05 m, the restoring force is -.05 k newtons.

If the mass is hanging from the band, it exerts a force of mg = .where the mass is in kg. So, the gravity force exactly balances the restoring force.

. .05*k = 0.225 x 9.8

K = 44.1 N /m

Answer 2

Hi Sammie:

For this, we need Hooke's Law: F = -kx where F = force applied, x - stretch distance, k = spring constant

So, 0.225g = -k (0.15 - 0.10) [note mass is in kg, distance in meters, g = gravitational accel = 9.8 m/s²

0.225 x 9.8 = -0.05 k

=> k = -0.225 x 9.8 / 0.05

= - 44.1

Done!