Two cars leave from the same place and head in the same direction. The first car travels 35 mph while the second car travels 40 mph. If the second car leaves one hour after the first car, how many hours will it take for the second car to catch up to the first?

Question

Two cars leave from the same place and head in the same direction.   The first car travels 35 mph while the second car travels 40 mph.   If the second car leaves one hour after the first car, how many hours will it take for the second car to catch up to the first?

whpalmer4 · Answer

The difference in speeds is 40mph - 35mph = 5mph.  The first car gets a lead of 35mph * 1 hour = 35 miles.  After the first hour, they both go 35 miles in an hour, plus the 2nd car goes an extra 5 miles, thus decreasing the lead by 5 miles every hour.  How many hours will it take to get the lead to 0?