In a balance calculation, removing an aft located item uses which expression?

In a balance calculation, removing an aft located item uses which expression?

• A. (-)weight X (+)arm (-)moment.
• B. (-)weight X (-)arm (+)moment
• C. (+)weight X (+)arm (+)moment
• D. (+)weight X (-)arm (-)moment

Answer: (C)

In weight and balance, the moment contribution of an item is calculated as weight × arm, and the sign of that moment depends on whether the item is forward or aft of the datum. Forward positions have negative arms, aft positions have positive arms, so items located aft produce positive moments. For an item that sits aft, its arm is positive, and its weight is a positive quantity, so the moment it contributes is a positive value. When you remove that aft-located item, you’re effectively subtracting that positive moment from the total, but the form used to represent the item's own contribution is weight × arm with positive signs, giving a positive moment. For example, a 60 lb item located 100 inches aft has a moment of +60 × +100 = +6000 in-lb. Removing it would reduce the total moment by 6000 in-lb, but the expression describing its contribution is positive weight, positive arm, yielding a positive moment.

In weight and balance, the moment contribution of an item is calculated as weight × arm, and the sign of that moment depends on whether the item is forward or aft of the datum. Forward positions have negative arms, aft positions have positive arms, so items located aft produce positive moments.

For an item that sits aft, its arm is positive, and its weight is a positive quantity, so the moment it contributes is a positive value. When you remove that aft-located item, you’re effectively subtracting that positive moment from the total, but the form used to represent the item's own contribution is weight × arm with positive signs, giving a positive moment.

For example, a 60 lb item located 100 inches aft has a moment of +60 × +100 = +6000 in-lb. Removing it would reduce the total moment by 6000 in-lb, but the expression describing its contribution is positive weight, positive arm, yielding a positive moment.