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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 (0.85 m high, 1.8 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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2007-07-31 09:39:13 · 1 answers · asked by Antonio E 1 in Science & Mathematics Physics

1 answers

Draw a diagram and you'll see that the window can be treated as a pixel that is passed across the wall starting from the corner A and through the corner B. You get a triangle where the height of the triangle is the height of the window, 0.85 m, and the base is the distance, d', the train travels before the lower corner on the leading edge of the window intersects the edge of the wall. The tangent of 12 is equal to h/d'.
or
d'=.85/atan(12)
The total distance, d, must also include the width of the window. or
d=d'+1.8

Now that you have d and you know v, compute t as
d=v*t or
t=d/v
plugging in

t=(1.8+.85/atan(12))/3
If you are using excel in radians mode, then use
atan(radians(12))

j

2007-07-31 10:08:06 · answer #1 · answered by odu83 7 · 0 0

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