| # MMLU-Pro | |
| Category: physics | |
| In a cloud chamber, a proton crosses at right angles a uniform magnetic field of 1.0 weber/m^2 . From the photograph of the proton's path the radius of curvature is measured as 0.22 m. Calculate the speed of the proton. | |
| A. 2.8 x 10^7 m/sec | |
| B. 4.0 x 10^7 m/sec | |
| C. 1.8 x 10^7 m/sec | |
| D. 2.5 x 10^7 m/sec | |
| E. 3.5 x 10^7 m/sec | |
| F. 3.0 x 10^7 m/sec | |
| G. 1.5 x 10^7 m/sec | |
| H. 1.0 x 10^7 m/sec | |
| I. 2.1 x 10^7 m/sec | |
| J. 2.3 x 10^7 m/sec | |
| Write your reasoning, then write the final option letter in final_answer.txt. | |