Answer:
Velocity is the displacement of an object divided by the time interval.
Explanation:
Let's consider each choices:
1. Velocity is not the magnitude of speed. Velocity is a vector quantity which means it consists of both direction and magnitude. Speed is the magnitude of velocity, not the other way around.
3. Velocity describes how fast an object is changing speed. If a speed changes each time interval, that is not a velocity but rather the magnitude of acceleration. Magnitude of acceleration is change in speed over time. Acceleration is the one that describes how velocity is changing through time.
4. Speed and velocity refer to the same vector quantity. Speed is not a vector quantity but a scalar quantity which only has magnitude. Speed is also considered as the magnitude of velocity as well.
Therefore, the only correct choice is 2. Velocity is the displacement of an object divided by the time interval. This is true since velocity is change in position (displacement) over time.