Question

Two fat astronauts each of mass 120 kg are travelling in a closed spaceship moving at a speed of 15 km/s in the outer space far removed from all other material objects.The total mass of the spaceship and its contents including the astronauts is 660 kg.If the astronauts do slimming exercise and thereby reduce their masses to 90 kg each,with what velocity will the spaceship move?

Answer 1

Since the spaceship is removed from any maternal object and totally isolated from surrounding,the mass loss by astronauts couldn't slip away from the spaceship.So the total mass of the spaceship remains unchanged and also its velocity.