My brother and I were discussing fuel consumption which lead to this thought experiment. Let's say you have two identically shaped spaceships of different masses traveling in outer space where they are not effected by any forces. No wind drag, no friction, no gravity, etc. Let's assume spaceship A has a mass of 1,000 Kg ans spaceship B has a mass of 10,000 kg. (it's filled with heavy stuff) Both are traveling side by side at 200 km/hr. Both ships will travel side by side at 200 km/hr forever unless they encounter other forces. Now if these spaceships suddenly hit a patch of air and experienced air friction similar to air pressure on earth. Which ship would need more energy to keep its speed constant at 200 km/hr. My brother argues that because ship B has more momentum the wind drag will affect it less and therefore need less energy to maintain it's speed. I'm arguing that the friction affects both ships equally with a certain force and the will both require an opposite and equal force to maintain their speed. What are your thoughts?