🔍 Key Concepts

• Free surface effect and how it is represented by a free surface constant (FSC) • Formula for second moment of area of a rectangle about a horizontal axis: I = (b · l³) / 12 (or similar form depending on orientation) • Effect of specific gravity of liquid and seawater on FSC (does S.G. cancel or scale the answer?)

💭 Think About

• Which tank dimension (length, breadth, or depth) is used as the "free surface" width in the moment of inertia formula for a slack tank? • When computing the free surface moment or constant, do you use the actual depth of liquid or the full tank depth, and why? • Check the units: which of the answer choices are consistent with typical magnitudes and units for a free surface constant on a vessel this size?

✅ Before You Answer

• Be clear which dimension you treat as breadth (B) and which as length (L) in the inertia formula; mixing them will give a very different value. • Confirm whether the free surface constant is usually expressed per unit density or already includes the liquid's specific gravity; this affects whether S.G. = 0.85 and seawater S.G. = 1.026 change the numeric result. • Double-check powers (squares vs. cubes) in the formula; an incorrect power will move you off by an order of magnitude and help you eliminate impossible answer choices.