# Velocity-time graphs

The velocity-time graph shows the time $$t$$ on the x-axis and velocity $$\vecphy{v}$$ on the y-axis. Similar to the displacement-time graph, the object is assumed to undergo linear motion with a defined positive direction.

Negative $$v$$ values would imply that the object is moving in the opposite direction.

The **gradient** of the graph gives the acceleration. Therefore, a horizontal line indicates that the object is moving at a constant velocity.

A **negative gradient** indicates that the velocity in the positive direction is decreasing.

The **area** between the graph and the line $$v=0$$ indicates the magnitude of displacement during the period.

If the graph crosses the t-axis and the area above is equal to the area below, the object has returned to its origin.