If $4 \mathrm {~J}$ Of Work Are Needed to Stretch a Spring From

Multiple Choice

If $4 \mathrm {~J}$ of work are needed to stretch a spring from $10 \mathrm {~cm}$ to $12 \mathrm {~cm}$ and another $20 \mathrm {~J}$ are needed to stretch it from $12 \mathrm {~cm}$ to $14 \mathrm {~cm}$ , what is the natural length of the spring? Round the answer to nearest integer.

A) $12 \mathrm {~cm}$
B) $8 \mathrm {~cm}$
C) $13 \mathrm {~cm}$
D) $11 \mathrm {~cm}$
E) $10 \mathrm {~cm}$