When the graph is a sloping straight line, like a positive slope, it indicates a constant acceleration. Say the slope is 2 m/s². This means the velocity of the object is increasing by 2 meters per second every second. If the initial velocity was 0, after 1 second it would be 2 m/s, after 2 seconds 4 m/s and so on. The steeper the slope, the greater the acceleration.
A velocity - time graph story is basically about interpreting the information shown on a velocity - time graph. The graph shows how the velocity of an object changes over time. If the graph is a straight horizontal line, it means the object is moving at a constant velocity. For example, a car moving at a steady 60 km/h would show this on the graph.
A horizontal line on the velocity - time graph means zero acceleration. It's like a car moving on a flat road at a constant speed, say 60 km/h. There's no change in its velocity, so no acceleration.
To create a velocity time graph story for simple harmonic motion, first, know that the velocity changes periodically. The graph oscillates between positive and negative values. When the displacement of the object is maximum (at the end points of the motion), the velocity is zero. As the object passes through the equilibrium position, the velocity is at its maximum or minimum depending on the direction. So, you could say 'Imagine a pendulum. At the far left or right, it stops for a moment (velocity = 0). As it swings towards the middle, it picks up speed, and as it passes through the middle, it has its highest or lowest speed depending on which way it's going.'
Well, in a distance - time graph story, a steep upward curve could represent rapid acceleration. Let's say a car starts from rest and quickly speeds up. This would show as the distance increasing rapidly over a short period of time on the graph. On the other hand, a downward - sloping line in a distance - time graph doesn't really make physical sense for normal motion because it would imply that the object is getting closer to the starting point as time goes on without going back in time. Usually, we see downward - sloping lines in cases like when we are considering the distance between two moving objects where one is catching up to the other.
First, look at the shape of the graph. A straight line indicates a constant acceleration. If it's a curve, the acceleration is changing. For example, in a parabolic velocity - time graph, the acceleration is not constant.
To analyze a distance - time graph story, check the slope. A positive slope means the object is moving forward. If the slope is zero, the object is stationary.
Suppose the graph has a curve that is concave up. This might represent an object that is accelerating. For instance, a rocket taking off. At the start, its displacement might increase slowly as it builds up thrust. But as time goes on and the thrust is more effective, it accelerates and the displacement changes more rapidly. The shape of the curve on the displacement - time graph can really tell us a lot about the motion of the object.
Think about a roller coaster. Initially, when it starts moving from the station, its speed is slow and gradually picks up. This is shown by the upward slope on the speed - time graph in the first minute or so. Then, it reaches a high speed and maintains that for some time, like for the next 2 - 3 minutes. Riders are screaming with excitement. As the ride nears the end, the speed decreases until it comes to a complete stop at the end of the track. All of these phases can be clearly seen and described using the speed - time graph.
First, look at the sign of the acceleration. Positive means speeding up, negative means slowing down. Then check the slope. Steep slope means high rate of change of acceleration. For example, in a graph of a ball thrown upwards, the acceleration is negative (due to gravity) and constant.