If a car is moving at 90 km/h and rounds a corner at 90 km/h, what remains constant?

The situation described involves a car moving at a speed of 90 km/h while rounding a corner at the same speed of 90 km/h. Speed is defined as the magnitude of velocity, which is the total distance traveled per unit of time regardless of the direction of travel. In this case, since the car maintains a speed of 90 km/h throughout the entirety of the turn, we can confidently say that the speed remains constant.

However, when a car rounds a corner, its direction changes continuously, resulting in a change in its velocity. Velocity is a vector quantity, meaning it has both magnitude and direction. Even though the speed (the magnitude of the velocity) remains at 90 km/h while rounding the corner, the direction of travel keeps changing, meaning that the velocity itself is not constant.

Since speed is the only quantity not affected by the change in direction during the turn, it remains constant at 90 km/h while the velocity, influenced by both speed and direction, does not. Thus, the answer that reflects the condition accurately is that the speed is constant.