Mass properties are properties (or characteristics) of a physical object that relate to its mass, or how much the object weighs. Mass properties tell us how heavy an object is, how dense (or how tightly packed together) the particles that make up the object are, and whether or not the object can move if a force is applied to it. Mass properties can help us better understand the world around us and how different objects interact with each other. For example, if you're playing catch with a ball and you throw it, the mass of the ball affects how fast it travels and which direction it goes when you throw it.