Two springs, one having spring constant $k_1 = 4\,\text{kN m}^{-1}$ and the other having spring constant $k_2 = 2\,\text{kN m}^{-1}$, are arranged as shown. What is the combined extension of the springs when they are supporting a load of $80\,\text{N}$?
- A$1.3\,\text{cm}$
- B$4\,\text{cm}$
- C$6\,\text{cm}$
- D$60\,\text{cm}$