Question

One more problem: A train leaves a station and travels at the rate of 40 mi/hr. Two hours later a second train leaves the station and travels at the rate of 60 mi/hr. Where will the second train overtake the first?

Answer 1

from the first train (A) we have:

S=So+Vo(t)
S=0+40(t) after two hours (when second train leaves) train A has traveled:
S=40(2)
S=80

In relation to the second train (B), train A starts at 80 so, rearranging Train A's eqt:
Sa = 80 + 40(t)

And from train B we have:
Sb = 0 + 60(t)

! The second train will overtake the first whenever Sa=Sb so,

80 + 40(t) = 60 (t)
20 (t) = 80
t = 80/20 = 4hr Ans.



Is tha right?

Answer 2

No, they want to know the place. Where will the second train overtake the first, not the duration.

Answer 3

oh misread the question, sorry.

you still have to make those calculations. With how much time they take to meet you plug it back in either equation A or B and it should give you the same answer:

Sa = 80 + 40 (4)
Sa = 80 + 160 = 240 mi

Sb = 60 (4) = 240 mi

So, The second train will overtake the first 240mi from the station