Displacement-Time and Velocity-Time Graphs

Displacement-Time Graphs

A displacement-time graph shows how an object’s position changes over time.
When the graph is a straight horizontal line, it indicates the object is at rest. The displacement remains constant over time.
A straight line sloping upwards suggests the object is moving at a constant velocity. The steeper the gradient of the line, the greater the velocity of the object.
On the other hand, a straight line sloping downwards indicates the object is moving backwards at a constant speed.
A curved line on this graph suggests the object is accelerating or decelerating. The steeper the curve, the greater the acceleration or deceleration.
The gradient of the line at any point on a displacement-time graph gives the velocity of the object at that instant.

Velocity-Time Graphs

A velocity-time graph shows how an object’s speed changes over time.
If the graph is a horizontal line, this indicates an object moving at a constant velocity.
A straight line with a positive slope signifies the object is accelerating. The steeper the gradient, the higher the acceleration.
Conversely, a straight line sloping downwards indicates the object is decelerating.
A curved line suggests the object’s acceleration is changing.
The gradient of the line at any point on a velocity-time graph gives the acceleration of the object at that moment.
The area under the graph between the time axis and the line represents the displacement of the object.

Understanding Graphs

Understand how to draw and interpret both displacement-time and velocity-time graphs to represent an object’s motion.
Remember that, in the context of physical movement, both displacement and velocity are vector quantities, which means they include both magnitude (how much) and direction (which way).
The shape of the line on the graph (straight or curved) and its gradient offer insightful information about the object’s motion. This data includes whether it’s moving at a constant velocity, accelerating, decelerating, or at rest. Similarly, the area under a velocity-time graph line gives the total displacement of the object.