What is the name of the physical quantity equal to mass times velocity?

• A. Velocity
• B. Momentum
• C. Acceleration
• D. Force

Answer: (B)

Momentum is the quantity equal to mass times velocity. It’s defined as p = m v, and because velocity is a vector, momentum is also a vector with the same direction as the motion. This means momentum measures how much motion an object has and how hard it would be to bring it to a stop—the larger the mass or the faster the object moves, the greater the momentum. Its units are kilogram meters per second. Momentum is a key concept in physics, with changes described by impulse (impulse equals the change in momentum, F Δt). The other ideas refer to different quantities: velocity is speed with direction, acceleration is how velocity changes over time, and force is what causes changes in motion.