* Velocity is a combination of speed (how fast something is moving) and direction.
Let's break down the answer choices. To figure out which doesn't describe a change in velocity, we need to think about whether speed, direction, or both are changing.
Here's how to analyze the actions:
* A car slowing down at a stop sign: This is a change in velocity because the car's speed is decreasing.
* A ball rolling down a hill: This is a change in velocity because the ball's speed is increasing.
* A plane turning left: This is a change in velocity because the plane's direction is changing, even if its speed stays the same.
* A satellite orbiting the Earth at a constant speed: This is a change in velocity. Even though the satellite's speed might be constant, it's constantly changing direction as it orbits the Earth.
Therefore, the action that does NOT describe a change in velocity is:
* An object moving at a constant speed in a straight line: Since both speed and direction are constant, the object's velocity isn't changing.
