Which statement about Specific Weight is true?

Which statement about Specific Weight is true?

• A. It equals mass per unit volume.
• B. It equals weight per unit volume.
• C. It is independent of gravity.
• D. It is the same as bulk density.

Answer: (B)

Specific weight is weight per unit volume. It is defined as gamma = W/V, where W is the weight (a force due to gravity) and V is the volume. Since weight equals mass times gravitational acceleration, gamma = rho * g. That means the value depends on gravity: on Earth it has a certain value, but on a body with different gravity it would change. This is why a statement about being independent of gravity is incorrect. It’s not mass per unit volume—that would be density, rho = m/V. It’s not the same as bulk density, which is mass per bulk volume including any voids; specific weight uses weight per volume instead of mass per volume. In practical terms, specific weight is the weight density used in pressure and buoyancy calculations, and its SI units are newtons per cubic meter.

Specific weight is weight per unit volume. It is defined as gamma = W/V, where W is the weight (a force due to gravity) and V is the volume. Since weight equals mass times gravitational acceleration, gamma = rho * g. That means the value depends on gravity: on Earth it has a certain value, but on a body with different gravity it would change. This is why a statement about being independent of gravity is incorrect. It’s not mass per unit volume—that would be density, rho = m/V. It’s not the same as bulk density, which is mass per bulk volume including any voids; specific weight uses weight per volume instead of mass per volume. In practical terms, specific weight is the weight density used in pressure and buoyancy calculations, and its SI units are newtons per cubic meter.