A car's speed rises from $10\,\text{m s}^{-1}$ to $15\,\text{m s}^{-1}$, causing its kinetic energy to increase by $E_1$. At a later time, its speed then rises from $15\,\text{m s}^{-1}$ to $25\,\text{m s}^{-1}$, causing its kinetic energy to increase by $E_2$. Find the ratio $\dfrac{E_2}{E_1}$?
- A$1.6$
- B$2.6$
- C$3.2$
- D$4.0$