A 50 g mass hanger hangs motionless from a partially stretched spring. When a 80 gram mass is added to the hanger, the spring stretch increases by 8 cm. What is the spring constant of the spring (in N/m)

Explanation:

The description of both systems can be done by means of the following two equations of equilibrium:

By diving the first expression by the second one, the following relation is found:

The initial elongation of the spring is:

The spring constant is found by substituting known variable in any of the two equations of equilibrium. For comfort and quickness reasons, the first formula is used:

the ima (higher than 1m) will be greater than the ima with the height of 1m.