In introductory kinematics, which quantity is defined as the rate at which velocity changes with time?

• A. Momentum
• B. Speed
• C. Displacement
• D. Acceleration

Answer: (D)

Verified step by step guidance

1. Understand the definitions of the given quantities: Momentum is the product of mass and velocity, Speed is the magnitude of velocity, and Displacement is the change in position.
2. Recall that velocity is a vector quantity that describes both speed and direction of motion.
3. Identify that the rate at which velocity changes with time is a fundamental concept in kinematics, describing how quickly an object's velocity changes.
4. Recognize that this rate of change of velocity with respect to time is called acceleration.
5. Therefore, acceleration is defined as the quantity that measures how velocity changes over time, mathematically expressed as \(\\vec{a} = \\frac{d\\vec{v}}{dt}\).