You drive your car 5.0 km due East at 35 km/hr,and suddenly realize that you forgot your wallet.So,you return home,driving West at 40 km/hr,and upon arrival spend 10 minutes looking for it,and finally go back on the road for a total of 57.0 km due East.If your average velocity was 40 km/hr for the whole journey,what was your average speed on your last leg.

Question

Quizplus · Accepted Answer

Average speed = Total distance/Total timeTotal distance = 5.0 km + 5.0 km + 57.0 km = 67.0 kmTotal time = 5.0 km/35 km/hr + 5.0 km/40 km/hr + 10 min + 57.0 km/40 km/hr= 0.143 hr + 0.125 hr + 0.167 hr + 1.425 hr= 1.86 hrAverage speed = 67.0 km/1.86 hr = 36.0 km/hr

You Drive Your Car 5