SOLUTION: A runner takes off at 5 feet per second. 30 seconds later another runner takes off at 7 feet per second. How long will it take for the 2nd runner to catch the first?
Algebra ->
Customizable Word Problem Solvers
-> Travel
-> SOLUTION: A runner takes off at 5 feet per second. 30 seconds later another runner takes off at 7 feet per second. How long will it take for the 2nd runner to catch the first?
Log On
Question 633447: A runner takes off at 5 feet per second. 30 seconds later another runner takes off at 7 feet per second. How long will it take for the 2nd runner to catch the first? Answer by dfrazzetto(283) (Show Source):
You can put this solution on YOUR website! d = v*t
v1 = 5 ft/s
v2 = 7 ft/s
second runner catches the first when their distances are equal
when second runner starts, first runner (v1) has been moving for 30 seconds
V1(t+30) = v2(t)
5(t + 30) = 7t
5t + 150 = 7t
2t = 150
t = 75 second
