A particle covers half of its total distance with speed $v_1$ and the rest half distance with speed $v_2 .$ Its average speed during the complete journey is
$\frac{{{v_1} + {v_2}}}{2}$
$\;\frac{{{v_1}{v_2}}}{{{v_1} + {v_2}}}$
$\;$ $\frac{{2{v_1}{v_2}}}{{{v_1} + {v_2}}}$
$\;\frac{{{v_1} + {v_2}}}{3}$
A car travels half the distance with constant velocity of $40\, kmph$ and the remaining half with a constant velocity of $60 \,kmph$. The average velocity of the car in $kmph$ is
A car moves from $X$ to $Y$ with a uniform speed $v_1$ and returns to $Y$ with a uniform speed $v_2$ . The average speed for this round trip is
A body has speed $V, 2\,V$ and $3\,V$ in first $1/3$ of distance $S$, second $1/3$ of $S$ and third $1/3$ of $S$ respectively. Its average speed will be :-
A train starting from rest first accelerates uniformly up to a speed of $80 \mathrm{~km} / \mathrm{h}$ for time $t$, then it moves with a constant speed for time 3t. The average speed of the train for this duration of journey will be (in $\mathrm{km} / \mathrm{h}$ ) :
A car travels a distance of $x$ with speed $v_1$ and then same distance $x$ with speed $v_2$ in the same direction. The average speed of the car is