Problema Solution
A plane takes off traveling east at 175mph. A jet takes off from the same airport, also traveling east, 2 hours later at 315 mph. When will the jet overtake the airplane?
Answer provided by our tutors
After two hours the plane's distance from the airport is x=v*t=175mph*2h=350 miles
The relative speed between the two aircrafts is v1=315-175=140 mph
Therefore, the time until they meet is 2.5 hours
t=distance/speed=350 miles / 140 mph = 2.5 h
Notes:
1. The only equation we used was distance = speed x time in various forms:
x=v*t, t=x/v
2. We also did one thing that is a little bit "clever", by looking at the relative speed between the two aircrafts. This saves us a variable and an equation.