Final answer:
True, velocity remains constant if acceleration is zero, as it includes both speed and direction. It's false that speed cannot remain constant if acceleration is not zero; speed can stay constant if directional changes occur such as in circular motion.
Step-by-step explanation:
Exploring Constant Velocity and Speed in Physics
Assessing the statements presented:
True: For the velocity to remain constant, the acceleration must remain zero. This is because velocity is a vector quantity, encompassing both magnitude and direction. If there is no change in speed or direction, the object is not accelerating.
False: For the speed to remain constant, the acceleration must remain zero. This is incorrect because speed is a scalar quantity, meaning it has no direction component. Speed can remain constant even if there is acceleration, as long as it is perpendicular to the direction of motion (as in uniform circular motion).
In the context of motion:
An object in linear motion with a constant velocity indicates both speed and direction are unchanging, thus acceleration is zero.
An object moving at a consistent speed may still experience acceleration if there is a change in the direction of motion.
If a displacement versus time plot is linear, it signifies zero acceleration since displacement changes uniformly over time.
Key principles highlight: Newton's laws of motion, explaining that in the absence of external forces (net force is zero), an object at rest stays at rest, and an object in motion stays in motion at a constant velocity.