Speed, Velocity, and Reading a Distance-Time Graph

Hi, I'm Lumi! Let's figure out how to describe and even predict the way things move. Two pieces of information do the whole job: speed and direction. Speed answers "how fast?" You find it by dividing the distance traveled by the time it took. If you walk 10 meters in 5 seconds, your speed is 10 ÷ 5 = 2 meters per second. Cover more distance in the same time, and your speed is higher. But speed alone is not enough to fully describe motion. When we include direction, we use the word velocity. Velocity = speed + direction. Imagine two buses both travelling at 30 km/h. If one heads north and the other heads south, they end up far apart — they have the same speed but different velocities! We can also show motion on a distance-time graph. Time goes along the bottom; distance goes up the side. A steep line means moving fast, a gentle line means moving slowly, and a flat line means the object has stopped. Once you know an object's speed you can predict the future: at 2 m/s, after 10 s it will have travelled 20 m. If you ever feel stuck, just ask two questions — "How fast?" and "Which way?" Those two answers give you the velocity, and that fully describes the motion.