# Forces and Motion: Velocity-Time Graphs

## Forces and Motion: Velocity-Time Graphs

• A velocity-time graph represents how an object’s speed changes over time. On this graph, the y-axis represents velocity and the x-axis represents time.
• If the line on the graph is horizontal (a straight line parallel to the x-axis), it means the object is moving at a constant velocity. The object is not accelerating or decelerating.
• If the line on the graph is straight and sloping upwards, it indicates that the object is accelerating. The steeper the slope, the greater the acceleration.
• If the line on the graph is straight and sloping downwards, it indicates that the object is decelerating or slowing down. Again, the steeper the slope, the higher the rate of deceleration.
• The slope of the line on a velocity-time graph shows the acceleration of the object. Thus, acceleration can be calculated by finding the gradient of the line: change in velocity / change in time.
• When the line descends below the time axis, it represents that the object is moving in the opposite direction, or has reversed its path.
• The area under the line in a velocity-time graph represents the distance travelled by the object. This can be calculated by finding the area between the line and the time axis.