Let's break down the question and the options provided.
Firstly, we need to understand that velocity is a vector quantity. This means it has both magnitude (speed) and direction. A valid velocity reading should include information about both the speed and the direction in which the object is moving.
Let's go through the options one by one:
1. 45 m/s
- This value gives us the speed of the object (45 meters per second), but it does not specify the direction. Therefore, this is not a complete representation of velocity.
2. 45 m/s north
- This value gives us both the speed (45 meters per second) and the direction (north). This is a complete and valid velocity reading because it includes both magnitude and direction.
3. 0 m/s south
- This value is interesting because it specifies a speed of 0 meters per second and a direction of south. Despite the given direction, the object is stationary, as its speed is 0. Still, it's a valid representation of velocity, since the direction does not negate the validity of the zero magnitude.
4. 0 m/s
- This value specifies the speed (0 meters per second) but again does not include the direction. While it correctly indicates that the object is stationary, it isn't a fully complete velocity reading due to the lack of directional information.
After examining each option, we conclude that both "45 m/s north" and "0 m/s south" are valid velocity readings. However, among these, the reading "45 m/s north" clearly stands out as it provides full and consistent information about both speed and direction in a non-zero context.
Therefore, a valid velocity reading for an object from the given options is:
45 m/s north
