91Ó°ÊÓ

Velocity is a vector quantity and is defined as the rate of change of displacement of an object with time. The SI unit of velocity is meter per second $\mathrm{m}/\mathrm{s}$.

The slope measures the steepness of a line in the graph. It is defined as the ratio of change in the y-coordinate to that in the x-coordinate.

The slope of a velocity versus time graph represents the acceleration. The slope at a particular time gives the instantaneous acceleration of the object.

The object starts at a speed of about $15\mathrm{m}/\mathrm{s}$and continues to move in the positive direction. It speeds up with a constant acceleration up to $t=45\mathrm{s}$, where its velocity at the highest point is $37\mathrm{m}/\mathrm{s}$.

The object then decelerates until it reaches an instantaneous acceleration of zero at $t=50\mathrm{s}$. It slows down in the positive direction from $t=50\mathrm{s}$to $t=90\mathrm{s}$. It takes a halt at $t=90\mathrm{s}$and stays at rest until $t=108\mathrm{s}$.

The object again gains some speed and moves to the right with greater acceleration. It then lowers the speed, giving less acceleration. Beyond $t=125\mathrm{s}$, the object continues to move faster toward the right direction.