Graphs in physics are pictures that show how an object moves over time.

Distance–Time Graphs

A distance–time graph shows how far an object travels as time passes. We plot time on the horizontal bottom line (the x-axis) and distance on the vertical side line (the y-axis). A flat horizontal line on this graph means the object is not moving; it is at rest. A straight diagonal line shows the object is moving at a steady speed. The steeper the line, the faster the object is moving. If the line curves upwards, the object is speeding up (accelerating).

Velocity–Time Graphs

A velocity–time graph shows how fast an object is moving and in what direction. Velocity is simply speed with a direction. In this graph, time stays on the bottom axis, but velocity goes on the side axis. A horizontal line here means the object is moving at a constant speed, not speeding up or slowing down. If the line slopes upwards, the object is accelerating. If the line slopes downwards, it is slowing down (deceleration).

Key Calculations

• Slope of distance-time graph: This equals the speed of the object.
• Slope of velocity-time graph: This tells us the acceleration, which is how quickly the speed changes.
• Area under a velocity-time graph: This total area represents the total distance the object has traveled.

Real-World Examples

Imagine a car stopped at a red light. On a distance–time graph, this is a flat horizontal line. When the light turns green and the car speeds up, the line on a velocity–time graph will climb diagonally. If the car drives at a steady speed on a highway, the velocity–time graph will show a flat line, showing no change in speed. Learning these graphs helps engineers design safer roads and helps scientists track the movement of planets and rockets.