The diagram depicts a uniform bridge that is $4.0\,\text{m}$ in length and has a weight of $10\,000\,\text{N}$. The bridge is pivoted at one end. At the other end, a force is increased slowly until the bridge just starts to rise. What is the lifting force when the bridge begins to move upwards?
- A$2500\,\text{N}$
- B$5000\,\text{N}$
- C$10\,000\,\text{N}$
- D$20\,000\,\text{N}$