How do you describe motion along a straight line?

Motion along a straight line is described by displacement, velocity, and acceleration, considering direction and magnitude.

When describing motion along a straight line, we start with displacement, which is the change in position of an object. Displacement is a vector quantity, meaning it has both magnitude and direction. For example, if you walk 5 metres to the east, your displacement is 5 metres east. This is different from distance, which only considers how much ground is covered, regardless of direction.

Next, we consider velocity, which is the rate of change of displacement. Like displacement, velocity is also a vector quantity. It tells us how fast an object is moving and in which direction. For instance, if a car travels 60 kilometres per hour to the north, its velocity is 60 km/h north. If the car changes direction but maintains the same speed, its velocity changes because the direction has changed.

Acceleration is the rate of change of velocity. It tells us how quickly an object is speeding up or slowing down. Acceleration is also a vector quantity. For example, if a car increases its velocity from 0 to 60 km/h in 10 seconds, it has an acceleration. If the car slows down, it has a negative acceleration, often called deceleration.

To analyse motion along a straight line, we often use graphs. A displacement-time graph can show how an object's position changes over time. The slope of this graph gives the velocity. A velocity-time graph shows how velocity changes over time, and the slope of this graph gives the acceleration. By understanding these concepts and using these tools, we can accurately describe and predict the motion of objects along a straight line.