Frank started out in his car traveling 45 mph. When Frank was 1/3 miles away, Daniel started out from the same point at 50 mph to catch up with Frank. How long will it take Daniel to catch up with Frank?

Guest Feb 18, 2021

#1**+1 **

Conversion factor from mph to ft - per - sec =

mph * 88 / 60

45 mph = 45 * 88 / 60 = 66ft/s

50 mph = 50 * 88 / 60 = 220/3 ft/ s

1/3 mile = 5280 ft / 3 = 1760 ft = the distance that Daniel must close to catch Frank

The difference in their rates = Daniel's effective closing rate = ( 220/3 - 66 ) ft/s

So....the time (in seconds) to catch Frank is

Distance to close / eff. closing rate

(1760) /( 220/3 - 66) = 240 sec = 4 min

CPhill Feb 18, 2021

#2**+2 **

Daniel has to cover 1/3 mile at the difference in speeds (5 m/hr) to catch up

1/3 m / 5 m/hr = 1/15 hr = 4 minutes

ElectricPavlov Feb 18, 2021