A rocket is moving straight up. It is acted on by three vertical forces. The thrust acts upwards and has a magnitude of $100\,000\,\text{N}$. The weight acts downwards and has a magnitude of $80\,000\,\text{N}$. What is the air resistance force on the rocket while it is moving upwards at a constant speed?
- A$20\,000\,\text{N}$ downwards
- B$20\,000\,\text{N}$ upwards
- C$180\,000\,\text{N}$ downwards
- D$180\,000\,\text{N}$ upwards