A person travels $x$ distance with velocity $v_1$ and then $x$ distance with velocity $v_2$ in the same direction. The average velocity of the person is $v$, then the relation between $v , v _1$ and $v _2$ will be :
The ratio of the numerical values of the average velocity and average speed of a body is always
A particle travels half of the distance of a straight journey with a speed $6 \,m / s$. The remaining part of the distance is covered with speed $2 \,m / s$ for half of the time of remaining journey and with speed $4 \,m / s$ for the other half of time. The average speed of the particle is ....... $m / s$
A particle moving in a straight line covers half the distance with speed $6 \mathrm{~m} / \mathrm{s}$. The other half is covered in two equal time intervals with speeds 9 $\mathrm{m} / \mathrm{s}$ and $15 \mathrm{~m} / \mathrm{s}$ respectively. The average speed of the particle during the motion is :
A car travels a distance $S$ on a straight road in two hours and then returns to the starting point in the next three hours. Its average velocity is