# Hanging Mass on Spring

## Homework Statement

A spring with spring constant k = 50 N/m and unstretched length of L is attached to the ceiling. A block of mass m = 1.5 kg is hung gently on the end of the spring. How far does the spring stretch?

PEspring=0.5kx2
Fspring=-kx

## The Attempt at a Solution

When the mass hangs at rest at its lowest point where the spring is stretched the furthest, its weight is exerting a force of 14.7 N on the spring. Likewise, the spring should be exerting that same force on the mass, but plugging that into the force equation by dividing 14.7 by 50 gives an x value of 0.29 m, but this is incorrect. I must be overlooking something since I know I probably have to use the potential energy equation too. Any know what I'm doing wrong?

## Answers and Replies

gneill
Mentor
Are there any particular units that they want the result expressed in? The force balance approach should be correct.

Oh, apparently I was right, it was the significant figures that were saying it was wrong. Thanks anyway!