Question

Two men decide to drive to a distant town, taking the same route. The first leaves 2 hours ahead of the second and drives at 60 km per hour, while the second man drives at 90 km per hour. How many hours will it take the second man to catch up with the first man?

Answer 1

Answer: 4 hours

Explanation:

2 x 60 =120

90-60=30

120/30= 4

Answer 2

`t = 6\,h`

Explanation:

Given that both men moves at constant speed on the same trail, the motion equations that describes each motion are, respectively:

Man 1

`x = 60 \cdot t`

Man 2

`x = 90 \cdot (t-2)`

Where x is measure in kilometers and t in hours, respectively.

The time taken for both men to meet each other is:

`60\cdot t = 90\cdot (t-2)`

`30\cdot t = 180`

`t = 6\,h`