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Physics Problem. I must find time. 
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#1
Aug3007, 09:52 PM

P: 457

1. The problem statement, all variables and given/known data
You are on a train that is traveling 3.0 m/s (to the left direction) along a level straight track. very near and parallel to the track is a wall that slopes upward at a 12 degree angle with the horizontal. As you face the windoes (.90 m high), (2.0 m wide) in your compartment, the train is moving to the left. The top edge of the wall 1st appears at window corner A and eventually disappears 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. 2. Relevant equations Time= distance/average speed 3. The attempt at a solution I multiplied .90 and 2.0 and I got .18m and then I divided it by 3.0 and I got .06 s. This is way off. What do I need to do. 


#2
Aug3107, 09:20 AM

HW Helper
P: 4,124

Why did you multiply the lengths?
You need to find the horizontal distance travelled... draw a picture... how do the window and wall look right as the wall appears... and draw another picture right when the wall leaves... What is the total horizontal distance? Hint: it is more than 2.0m. you'll need a little trig. Once you get the distance, divide by velocity to get time. 


#3
Aug3107, 09:35 AM

Math
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Thanks
PF Gold
P: 39,682

?? Even your multiplication is wrong: if the window has width 2.0 m and height 0.9 m, then it has area 1.8 m^{2} but that has nothing to do with the problem.



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