Define acceleration , average acceleration and instantaneous acceleration.
The time rate of change of velocity is called acceleration.
Let a particle be moving in a straight line and at time $t_{1}$ and $t_{2}$ its velocities are $v_{1}$ and $v_{2}$ respectively. Thus, the change in velocity of the particle in time interval $\Delta t=t_{2}-t_{1}$ is $v_{2}-v_{1}$. According to definition of average acceleration,
$\text { Average acceleration }=\frac{\text { change in velocity }}{\text { time }}$
$\therefore\langle a\rangle=\frac{v_{2}-v_{1}}{t_{2}-t_{1}}=\frac{\Delta v}{\Delta t}$
Average acceleration is a vector quantity and its direction is in the direction of change in velocity $(\Delta v)$.
Taking $\lim _{\Delta t \rightarrow 0}$ in equation then we get instantaneous acceleration $a$ at time $t$.
The velocity-time and acceleration-time graphs of a particle are given as Its position-time graph may be gvien as
The motion of a body is given by the equation $\frac{{dv(t)}}{{dt}} = 6.0 - 3v(t)$. where $v(t)$ is speed in $m/s$ and $t$ in $\sec $. If body was at rest at $t = 0$
The diagram shows the variation of $1 / v$ (where, $v$ is velocity of the particle) with respect to time. At time $t=3\,s$ using the details given in the graph, the instantaneous acceleration will be equal to $...........m/s^{2}$
For the acceleration-time $(a-t)$ graph shown in figure, the change in velocity of particle from $t=0$ to $t=6 \,s$ is ........ $m / s$