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The mass of an aircraft is 2000 kg and 400 kg of freight is added to a hold 2 m aft of the present CG position, the movement of the CG is:
• A
0.4 m aft.
• B
0.33 m forward.
• C
0.33 m aft.
• D
0.4 m forward.

Adding mass aft of the present CG position, will alter both the total mass and the total moment, causing the Centre of Gravity to relocate more aft.

The following formula helps to find out by how much the CG will relocate after adding a freight of 400 kg, 2 metres aft of the present CG position: Mass Change / New Total Mass = Change of CG / Distance from mass to the old CG.

Solving for Change of CG we get: Change of CG = (Mass Change x Distance from mass to the old CG) / New Total Mass = 400 kg x 2 m. / (2 000 kg + 400 kg) = 0.33 m aft.

Alternatively: New Total Moment = Old Total Moment + Moment of Mass Added ⇒
(2400 kg) × (Old CG + CG movement) = (2000 kg × Old CG) + [400 × (Old CG + 2 m.)].

Solving for CG movement, we get 0.33 m. aft.

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