 Using graphs to explain motion. Observation is part of what we do every day. In physics, observing and describing what we see is key to understanding. The trick is that each of us may have made the same observation, but describe it differently. In this activity, you will observe the motion of the two trucks shown below. Let's take a look. Pay close attention to the movement of each truck as we watch again. How is the movement of the two trucks the same? They're both moving in the same direction. Both trucks are moving from left to right. How is the movement of the two trucks different? The red truck moves at a consistent speed, while the blue truck starts slower than the red truck and starts to fall behind. As time goes on, the blue truck gains speed and passes the red truck. A common way for people to describe motion is to use specific measurements. Using those measurements to describe how far or how fast the truck was going can allow a person who is not there to understand what happened. When distance or velocity keeps changing, graphs can be used to record the data, as seen in the example below. Here we show the data graph for the distance, velocity, and acceleration of the two trucks shown earlier. Use your observations to select which line represents which truck in each graph. Based on the graph below, which line represents the blue truck and which line represents the red truck? The red truck is consistent in speed as represented by the black line, so the yellow line represents the blue truck. Based on the graph below, which line represents the blue truck and which line represents the red truck? The yellow line represents the blue truck. Its velocity increases over time. The black line represents the red truck because the velocity was constant over time. Based on the graph below, which line represents the blue truck and which line represents the red truck? The yellow line represents the blue truck because the acceleration was slower at the start and faster at the end. The black line represents the red truck whose acceleration was unchanged while in motion. Graphing is a powerful tool for showing trends of previous occurrences and for making predictions of what may happen next. This concludes this learning activity using graphs to explain motion.