A cow is standing 5 feet from the middle of a bridge. A train is coming towards the cow at 90 mph from the near end and the train is twice as long as the bridge. If the cow tries to move forward in same direction as train, cow is hit by 3 feet. But it moved in the opposite direction and was saved by 1 feet. What is the length of the bridge? Describe the cows gait.
2006-08-15 08:32:56 · 11 answers · asked by babydoll 1 in Science & Mathematics ➔ Mathematics
.Damn, I was really wanting a hamburger.
12 feet, but this is a fairy tale, since there are not any trains 24' long. and certainly none that can cruise at 90. The cow must have taken a dump when that happened.
2006-08-15 08:38:15 · answer #1 · answered by Anonymous · 0⤊ 2⤋
Interesting question. I like! Sorry, none of the above answers is correct. Here's how you solve it.
Make a diagram so you can visualise the problem. Let the length of the bridge be x ft. The middle of the bridge is x/2 ft. The cow is standing at point 'C', at a distance x/2 - 5 ft. from the near side.
To solve the problem we have to assume that the cow moves in either direction at the same speed. If the cow moves towards the train, it escapes by 1 ft., that is, to a point 'E' 1 ft. away from the bridge. In this case, the cow moves a distance (x/2 - 5) + 1 = x/2 - 4 ft.
But if the cow moves away from the train, it gets hit at a point 'H' 3 ft from the far end of the bridge. Since this is 3 ft. less than the length of the bridge we represent it as x - 3. The distance traveled by the cow in this case, from C to H, is (x - 3) - (x/2 - 5) = x/2 + 2 ft.
Now x/2 + 2 is 6 feet greater than x/2 - 4. So the cow moved 6 ft in the time it took for the train to travel from E to H (Imagine 2 cows running in opposite directions - one reaches point E and escapes, the other has some extra time to run while the train moves from E to H, but is still hit).
The distance from E to H is (x/2 - 4) + (x/2 + 2) or (x -2). The train is moving at 90 mph, which works out as 132 ft. per second. The train moves from E to H, or (x - 2) ft. in the same time it took the cow to move 6 ft. The train moves 6 ft in 0.045 seconds.
2006-08-15 11:47:03 · answer #2 · answered by multidisciplinarian 3 · 0⤊ 1⤋
First step is to convert the 90 mph to feet per second.
Second step, is to create two equations, with both outcomes for the cow.
Define positions of the cow as P(0) = 1/2(Bridge Length)-5 ft.
(distance from start of bridge)
_____ P(1) = 3 ft (3 ft from the start of the bridge)
________(this is also P(0) - 3 ft.)
_____ P(2) + Bridge Length + 1 ft. (1 ft from the end of the bridge)
From there, you should have two equations with two time frames.
Hope that helps.
2006-08-15 08:47:16 · answer #3 · answered by Jim T 6 · 1⤊ 0⤋
I'm not sure about the length of the bridge, but I would image the cow's gait could be described as "RUN LIKE HELL"
Incidentally, the length of the train is irrespective. Examiners just put things in like that to confuse you. It's only the front of the train that is going to go SPLATT!!
2006-08-15 08:45:30 · answer #4 · answered by Anonymous · 1⤊ 0⤋
the cow stepped to the side of the tracks
2006-08-15 08:38:13 · answer #5 · answered by Astro Gurl 3 · 0⤊ 1⤋
Wow
2006-08-15 08:38:04 · answer #6 · answered by praehunter 2 · 0⤊ 0⤋
I don't recall seeing anything quite like that on the quant section, and I scored nearly perfect. If you did see something that nasty, it would likely be at the end. Guessing may be your best bet.
2006-08-15 08:54:44 · answer #7 · answered by a_liberal_economist 3 · 0⤊ 1⤋
3808.5 feet with the cow moving at 1fps (Ihope)
2006-08-15 08:42:32 · answer #8 · answered by aggravatingprick 4 · 0⤊ 1⤋
you need to get out more.
2006-08-15 08:38:32 · answer #9 · answered by kevin m 2 · 0⤊ 1⤋
ahh! your mom is on a bridge? ahh!
2006-08-15 08:45:36 · answer #10 · answered by whosyourdaddy 3 · 0⤊ 3⤋