Mechanical Efficiency and Friction
Machines cannot perform at their 100%. Scientists say that if there were no friction in our planet we could have achieved 100% of mechanical efficiency. Why do you think objects in space stay in motion unless an equal or greater force acts upon them? It’s because there’s no friction in space. For example, when you roll a ball in space, it will constantly roll unless an object bigger or of equal force stops it. Remember Newton’s Laws of Motion? On the other hand, if you roll a ball here on earth no matter how much strength you exerted to push it, it will eventually stop even if no force acts upon it. This is because of friction.