The velocity-time graph for a particle moving in a straight line is shown in the figure. The average velocity between $t=4 \,s$ and $t=6 \,s$ is . . . . . . (in $\,ms^{-1}$)

Explain instantaneous velocity.

Velocity of a particle moving along a straight line is given by $v = t^2 - 3t - 4 \, (m/s)$. Find the velocity at the instant when no net force is applicable on the particle.......$m/s$ (in $.25$)

The speed versus time graph for a particle is shown in the figure. The distance travelled (in $m$) by the particle during the time interval $t=0$ to $t=5\, s$ will be

Among the four graphs shown in the figure,there is only one graph for which the average velocity over the time interval $(0, T)$ can vanish for a suitably chosen $T$. Which one is it?

In the picture shown,a ball starting from rest rolls down a ramp $AB$,moves along the horizontal bottom $BC$,then goes up a smaller ramp $CD$,and thereafter rolls on the horizontal plane $DE$. Ignore friction and air resistance. Which of the following figures shows the variation in speed with time?