Bob observes his phone dangling from a cord while the train he is in accelerates out of the station, lasting about 18 s. If the cord forms an angle of 26° with respect to the vertical during this acceleration, estimate the speed of the train at the end of the 18 s.

• A. 75 m/s
• B. 86 m/s
• C. 90 m/s
• D. 97 m/s

Answer: (B)