Question 4758: Two cars labeled A and B are in a 500 lap race. Each lap is 1 mile. The lead car, A, is averaging 125 mph when it reaches the halfway point. Car B is exactly 6.2 laps behind.
a) What is the average speed of car B?
b) When car A reaches the halfway point, how far behind, in seconds, is car B from car A?
Answer by longjonsilver(2297)   (Show Source):
You can put this solution on YOUR website! car A travels at 125mph and goes half-distance --> 250 laps --> 250 miles, so it has taken 250/125 = 2hours.
a) In the same time (2 hours) car B is 6.2 laps (6.2 miles) behind, so it has travelled only 243.8 miles so far. Its speed is therefore 243.8/2 = 121.9mph.
b) by this i take it it means how long will it take B to reach halfway? Well its speed is 121.9mph and it needs to travel a further 6.2 miles, so it will take 6.2/121.9 = 0.05086 hours which is 3minutes 5 seconds.
Jon.
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