What term refers to the mass per unit volume of a substance?

What term refers to the mass per unit volume of a substance?

• A. Density
• B. Elasticity
• C. Noise
• D. Echo

Answer: (A)

Density is the mass per unit volume of a substance. It tells you how much matter is packed into a given space, calculated as ρ = m/V. The common units are kilograms per cubic meter (kg/m^3) or grams per cubic centimeter (g/cm^3). For solids and liquids, density stays fairly constant under normal conditions, while for gases it changes with temperature and pressure. A material with high density has a lot of mass in a small volume, like metal, whereas a low-density material is more spread out, like wood or air. This concept explains why a metal block feels heavy for its size compared to a similarly sized wooden block. The other terms refer to different properties—elasticity involves deformation and recovery, while noise and echo relate to sound characteristics.

Density is the mass per unit volume of a substance. It tells you how much matter is packed into a given space, calculated as ρ = m/V. The common units are kilograms per cubic meter (kg/m^3) or grams per cubic centimeter (g/cm^3). For solids and liquids, density stays fairly constant under normal conditions, while for gases it changes with temperature and pressure. A material with high density has a lot of mass in a small volume, like metal, whereas a low-density material is more spread out, like wood or air. This concept explains why a metal block feels heavy for its size compared to a similarly sized wooden block. The other terms refer to different properties—elasticity involves deformation and recovery, while noise and echo relate to sound characteristics.