What is an object that is devoid of electrons and protons?

In a heat engine if 1000 j of heat enters the system and the piston does 500j of work, what is the final internal energy of the system if the inital energy was 2000 j1.write the equation2.list out your known variables 3. plug the numbers into the equations4.solve 5.write your solution statement that includes initial energy and final energy added.

20) what is a magnetic field? 21) in which direction do magnetic field lines always point? 22) sketch a diagram showing how a plotting compass points around a 23) name two magnetic poles that will: a) attract each other b) repel each other. 24) explain why you can use a compass to navigate. 25) what's an electromagnet? 26) list two ways to increase the strength of an electromagnet. 27) the wire in a simple motor feels a force when a current flows through it. why is this? i need answers to check mine

Why is the basic problem of economic,scarcity, a universal problem?