Question

A body travelling along a straight line one-third of the total distance with a velocity $4m/s$. The remaining part of the distance was covered with a velocity $2m/s$ for the first half of the remaining journey and with a velocity $6m/s$ for the another half of the remaining journey. The average velocity is

• A. $5m/s$
• B. $4m/s$
• C. $4.5m/s$
• D. $3.5m/s$

Answer 1

Answer: (B)

$4m/s$

Let total distance d
Let time covered for first one third distance be$t_1$
Then $t_1=\frac{d/3}{4}=\frac{d}{12}$
$t_2$ be time for next two journeys
$d-\frac{d}{3}=\frac{2d}{3}=2t_2+6t_2=8t_2$
$t_2=\frac{d}{12}$
$Averagevelocity=\frac{Totaldistane}{Totaltime}=\frac{d}{t_1+2t_2}=\frac{d}{\frac{d}{12}+\frac{2d}{12}}=4m/s$