Final Answer:
Before turning around, the car's velocity is +30 m/s (East), and after turning around, the velocity is -30 m/s (West).
Step-by-step explanation:
When the car is moving East with a speed of 30 m/s, its velocity is considered positive along the x-axis. This is denoted as vₓ = +30 m/s, where the positive sign indicates the direction (East). When the driver turns around and starts moving West, the velocity is now in the opposite direction. Since West is considered the negative direction along the x-axis, the velocity becomes vₓ = -30 m/s. The magnitude of the velocity remains 30 m/s, but the negative sign indicates the change in direction to the West.
In physics, velocity is a vector quantity that includes both magnitude and direction. The sign convention helps us understand the direction of motion. In this scenario, positive velocity indicates motion to the East, and negative velocity indicates motion to the West. The change in sign represents the reversal of direction when the car turns around. The magnitude of the velocity before and after turning remains the same at 30 m/s, but the direction is different.
In summary, the car's velocity before turning around is +30 m/s (East), and after turning around, it becomes -30 m/s (West), reflecting the change in direction while maintaining a constant speed.