At rest, when travelling at a constant speed, and when in mechanical equilibrium, there is no acceleration and answer choice D is correct.
<h3>How would you define acceleration?</h3>
In mechanics, acceleration describes the rate at which a driving object's velocity changes over time. They are accelerations and vector quantities. The direction of an object's acceleration is determined by the direction of the net force acting on it. Depending on whether an object is moving faster, slower, or in a different direction, its velocity may change. Examples of acceleration include a falling apple, the moon orbiting the earth, and a car that has stopped at a stop sign. The car is positively accelerating if the speed is increasing. As the car slows down, its speed decreases. A decline in speed is referred to as negative acceleration. In both situations, the car is traveling ahead, yet one has a positive acceleration and the other a negative one.
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