Question

A train leaves Chicago for Los Angeles going a constant rate of 40 MPH. Two hours later, another train leaves Chicago for Los Angeles on the same track as the first going a constant rate of 60 MPH.

1. When will the 2nd train catch up to the first train?

2. How many miles will the trains have traveled when they meet?

Answer 1

1 . 4 hrs , 2 . total 400 miles because the first train had travelled 160 miles and 2nd one had travelled 240 miles

Explanation:

in 1. use relative motion concept I. e. you sir on 1st train and put velo. of same mag. and in oppo. direction on the train on which you have sit and do the same with the velocity only with 2nd train means you stop the train on which you are sitting and put the velocity of the train on which you are sitting on 2nd train but in oppo. direction , so now the relative velocity comes out to be 20 mph and then apply formula time = Srel / Vrel and here we can find S rel by multiplying the velo. of 1st train by given time I. e. 2 hrs and in 2. multiply the time calculated by us by the velocity of both trains and by which you get the dist. travelled by both trains and then add them to get final answer.