A rocket is moving vertically upwards. Three vertical forces act on it. The thrust acts upwards and is equal to $100\,000\,\text{N}$. The weight acts downwards and is equal to $80\,000\,\text{N}$. What is the force of air resistance on the rocket when it is moving upwards at 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