A solid object with mass $1.0\,\text{kg}$ is moving straight down in a vacuum. At the moment its speed reaches $60\,\text{m s}^{-1}$, an extra constant force of $50\,\text{N}$ begins to act on the object vertically upwards. Find the speed of the object $2.0\,\text{s}$ after this additional force starts acting.
- A$20\,\text{m s}^{-1}$
- B$40\,\text{m s}^{-1}$
- C$80\,\text{m s}^{-1}$
- D$100\,\text{m s}^{-1}$