Question

why a body of mass 5 kg can be escalated more easily by a force then another body of mass 50 kg under similar conditions

Answer 1

because the rate of escalation is inversly proportional to mass,lesser the mass higher the object is escalated

Answer 2

the added weight on the 50 kg from gravity, will be escalated slower than the 5 kg item, because with size and mass being bigger than that of the latter, it would reasonably take more force to move the object or item, if you were to push a 50 kg object with only say 5 newtons, the object wouldn't move but instead feel like a wall, because newtons law of action and reaction says that a bigger object will push back harder, so it would take more force to cause the escalation to increase, however its large mass and slow escalation means its also a slower deescalation, or slowing, the object would be much easier to stop as well if the object was smaller.