### Video Transcript

When a particle moves in a straight line in a constant velocity, the magnitude of its acceleration what.

We can demonstrate what a constant velocity would look like by looking at a velocity–time graph. If a particle was moving in a straight line in a constant velocity 𝑉 sub one, then the corresponding graph would be a horizontal line as shown. We know that the acceleration on a velocity–time graph is its slope or gradient. Any horizontal line has a slope equal to zero.

We can therefore conclude that when a particle moves in a straight line in a constant velocity, the magnitude of its acceleration is zero. If our velocity–time graph has a positive slope, we will have a constant acceleration. In a similar manner, if the slope of our straight line is negative, the body will travel with a constant deceleration. When dealing with curved velocity–time graphs, our acceleration can increase and decrease.