**13. You are on a train that is traveling at 3.0 m/s along a level straight track. Very near and parallel to the track is a wall that slopes upward at a 12° angle with the horizontal. As you face the window (0.90 m high, 2.0 m wide) in your compartment, the train is moving to the left, as the drawing indicates. The top edge of the wall first appears at window corner A and eventually disappears at window corner B. How much time passes between appearance and disappearance of the upper edge of the wall?

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Problem 13

There are two horizontal differences we need to consider.  The width of the window (2.0 m) is obvious.  The other distance is how far horizontally the window moves for the wall to travel up the 0.90 m.  Consider the diagram below

So we need to know , we know , use

 

 

So the total distance that must be traveled horizontally is L = 4.23 m + 2.0 m = 6.23 m

 

 

 

 

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This page last updated on January 11, 2020