A motor vehicle travelled the first 1/3 of a distanceat a speed of v_(1)=10kmph, the second 1/3 at a speed of v_(2)=20kmphand the last 1/3 at a speed of v_(3)=10kmph. Determine the mean speed of the vehicle over the entire distance s .

A motor vehicle travelled the first 1/3 of a distanceat a speed of v_(

1.	A motor vehicle travelled the first 1/3 of a distanceat a speed of v_(1)=10kmph, the second 1/3 at a speed of v_(2)=20kmphand the last 1/3 at a speed of v_(3)=10kmph. Determine the mean speed of the vehicle over the entire distance s .
Answer» Solution :`v_(1)=10kmph, v_(2)=20,v_(3)=60,v=?` `3/v=1/v_(1)+1/v_(2)+1/v_(3),3/v=1/(10)+1/(20)+1/(60)=0.1+0.05+0.016` `:.v=3/(0.166)=18KMPH`