manimgoindowndown wrote:
Hey Bunuel so something I sort of missed was why we combine the rate (understood this) but then to figure out the time the trains cross each other to simply divide the distance z by the combined rates?
The distance z is the total distance for A to B. Which is different for what we're looking for, no? Aren't we looking for the time (and hence corresponding) distance where A and B cross each other?
Two trains are traveling to meet each other.
Distance = 100 miles;
Rate of train A = 20 miles per hour;
Rate of train B = 30 miles per hour.
In how many hours will they meet?
(Time) = (Distance)/(Combined rate) = 100/(20+30) = 2 hours.
Does this make sense?[/quote]
Combining the rates makes sense to me, they are both moving to each other relatively
Here's what doesn't make sense to me.
The distance between the two starting points of the train is 100 miles (z). If we are trying to find what time they will pass each other, that distance MUST BE less than 100 if both trains have a positive velocity.
This distance is less than the starting points of the train from 100 miles (z)?
So I don't see how we can simple plug in z here. Maybe there's a test assumption that simplifies this situation for us.[/quote]
"Pass" here means "meet".