Momentum is calculated by multiplying speed and which quantity?

• A. Weight
• B. Distance
• C. Time
• D. Mass

Answer: (A)

Momentum is a measure of how hard it is to change an object’s motion, and it depends on both how much matter the object has and how fast it’s moving. The quantity that multiplies speed to give momentum is mass. In physics, momentum equals mass times velocity (p = m v), where velocity includes both speed and direction. Mass represents the object's inertia—the resistance to changes in motion—so it sets how much momentum the object has for a given speed. Using weight would mix in gravitational effects and isn’t a direct measure of an object’s inertia, so it wouldn’t consistently produce momentum. Distances or time aren’t the factors that scale momentum either, since speed already blends distance and time, and momentum uses velocity to include direction.