Hint: length of arc = 40/360 * pi(2*1800) = pi(3600) / 9 = ?
A railroad track is laid along the arc of a circle of radius 1800. The circular part of the track subtends a central angle 40 degrees. How long in Sec will it take s point on the front of the train moving at 30 mph to go around this portion.
I'm given: Radius-1800 Theta-40 Velocity-30. So, would I use V=r(theta)/time. Then, divide by 60 time to convert to seconds.
Your speed is given in miles per HOUR -- 3600 seconds in a hour.
You can determine the arc length: feet.
(Wilmer gave you that -- I just did the division of 3600 by 9 to leave 400.)
The speed: 30 mph is equivalent to:
=
Then divide the arc length by the speed:
to get the time in seconds to traverse the arc.