Answer:
The right answer is: The marble moved 30cm north in 6 seconds
Step-by-step explanation:
A complete scientific description of the movement of an object includes its magnitude (speed, in this case) and direction of this one. With those two parameters, we can define the velocity vector of that object.
Explanation of the posible right answers:
- ✘ The ball rolled 20cm in 5 seconds: It's not the right answer because although with that information we can talk about the speed, it doesn't indicate information about the direction of the movement (necessary to know velocity, a more complete scientific description).
- ✘ The marble changed position quickly: It indicates there is a high speed, but not its magnitude and direction, both necessary to a complete scientific description). That's why it's not the right answer.
- ✘ The car traveled north: It only talks about the direction of the movement, but not its magnitude. It's not the right answer.
- ✓ The marble moved 30cm north in 6 seconds: Of the four options, it's the one which provides the more complete scientific description of an object in motion, because it clearly defines the magnitude and direction of the movement (with which we can determine the velocity vector).