In introductory mechanics, what causes a change in an object's velocity (magnitude and/or direction)?

• A. Acceleration
• B. Velocity
• C. Constant position
• D. Mass

Answer: (A)

Verified step by step guidance

1. Recall the definition of velocity: it is a vector quantity that describes both the speed and direction of an object's motion.
2. Understand that a change in velocity means a change in either the speed (magnitude) or the direction of the object, or both.
3. Recognize that acceleration is defined as the rate of change of velocity with respect to time, mathematically expressed as \(\\vec{a} = \\frac{d\\vec{v}}{dt}\).
4. Therefore, any change in an object's velocity is caused by acceleration, which can result from forces acting on the object according to Newton's second law.
5. Conclude that among the given options, acceleration is the correct cause of a change in velocity.