If a subway train is moving to the left (has a negative velocity) and then comes to a stop, what is the direction of its acceleration? Is the acceleration positive or negative?
It has to be opposite to the direction of motion if it is slowing down.
To determine the direction of acceleration, we need to consider the change in velocity. In this case, the subway train is moving to the left, which means the initial velocity is negative. When the train comes to a stop, the velocity changes from negative to zero.
Since the velocity is changing from negative to zero, the train is slowing down. Therefore, the direction of acceleration is opposite to the direction of velocity. In this case, the acceleration is positive because it acts in the positive direction to oppose the negative velocity and bring the train to a stop.
To determine the direction of acceleration when a subway train comes to a stop, you need to consider its initial velocity and final velocity.
In this case, the subway train is moving to the left, which means it has a negative velocity. When the train comes to a stop, its final velocity becomes zero.
Acceleration is the rate at which velocity changes. If the final velocity is zero and the initial velocity is negative, it means the train is slowing down.
Since the train is decelerating or slowing down, the direction of its acceleration is opposite to its initial velocity, which means it is positive.
Therefore, the acceleration of the subway train, when it comes to a stop, is positive.