Momentum is the product of an object's speed and _____.

• A. weight
• B. radius
• C. volume
• D. density

Answer: (A)

Momentum measures how much motion an object has, and it depends on both how much matter is there and how fast that matter is moving. The correct way to complete the idea is that momentum equals mass times velocity (or speed, since speed is the magnitude of velocity). Mass is the amount of matter, and velocity is how fast and in what direction that matter is moving, so their product tells you how much motion the object carries.

Weight, the force gravity exerts on a mass, isn’t the same as mass and can change with gravity. Radius and volume are geometric properties and don’t by themselves determine motion. Density is mass per unit volume, which relates to how compact the matter is but doesn’t directly tell you the total momentum unless you also know the total mass and the speed.

So the concept you’re after is p = m v, where m is mass and v is velocity (or speed). None of the listed options directly matches that complete relationship because mass isn’t among them.