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Problema Solution

the distance necessary to stop a subway train at a given speed is inversely proportional to its deceleration. If a train is traveling at 30 mph requires 180 ft to stop when decelerating at 0.18g, what is the stopping distance at the same speed when it is stopping at 0.15g?

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Answer provided by our tutors

Let

d = deceleration

s = the distance

x = the stopping distance that we need to find

The distance stopping at a given speed is inversely proportional to its deceleration means:

s*d = C, where C is constant

Now we use the given information:

180*0.18g = x*0.15g

0.15gx = 180*0.18g divide both sides by g

0.15x = 180*0.18

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click here to see the equation solved for x

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x = 216 ft

The stopping distance for a train traveling 30 mph with deceleration 0.15g is 215 feet.