While traveling at 65 mph, a car passes a train from the back to the front in 2 minutes. At the same time, another car, also traveling at 65 mph, moves from the front to the back of the train in 10 seconds. If the train travels at a constant speed, how long is the train?
I don't know how to attack this problem, can someone give step by step directions?
THANK YOU!!!
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Car A: Traveling w/ Train at 65mph
Car A travels from back to front in 2 minutes
Car B: Traveling against Train at 65mph
Car B travels from front to back in 10 seconds.
You start every physics question by writing down every equation you know.
NOTE: You know: Distance = Speed * Time (You will use this later).
Now, on to the problem:
Part 1:
The speed of the car is 65. The speed of the train is x.
Because the train and Car A is traveling in the same direction, the difference (multiplied by time) will yield the distance of the train.
(65mph - x mph)*(1/30) = Y; the distance of the train.
Why do we multiply by 1/30? The answer is because it takes the car 2 minutes to pass the train. This means that we need to adjust by time (2/60 = 1/30).
Part 2:
We can draw a similar relationship with Car B and the Train. Car B is also traveling at 65 mph, but the train is traveling in the opposite direction. Therefore the sum of these two speeds yields the speed of the car with respect to the train. (65 + x). We know it takes 10 seconds for the car to travel the train front to back so the distance it travels is given by:
(65 mph + x mph)*(10/3600) = Y (distance of the train).
(The reason we multiply by 10/3600 is because there are 3600 seconds in an hour. By multiplying by 10/3600 we are calculating the distance covered).
How do we solve the problem from here?
Set one equation equal to the other. Why?
Y represents the distance of the train so setting them equal will allow us to solve for x.
(65 - x)*(1/30) = (65+x)*(10/3600)
Once you have x, plug it in any of the two equations to get Y (the length of the train).
Hope I haven't confused you,
-LG
Train travel time= K= constant.
THEN THE
Car is =K+120second Remeber they both are moving.
The second car is =K+10second.
We know that the different in second is 110 seconds.
I can't tell how long is the train since theres no units. But I can find the movespeed of the car. but thats will totally neglect the question. Think the question is meant to ask, or compare the different of speed between those two cars. not the train.