A closed system is a system that is completely isolated from its environment. The physical universe, as we currently understand it, appears to be a closed system. An open system is a system that has flows of information, energy, and/or matter between the system and its environment, and which adapts to the exchange.
D makes the most sense, but you just have to put two and two together and go with your gut feeling, first cross out the answers that don't make sense (A didnt make sense) and go from there! I hope the little bit above me helped you answer or decide :) Good luck!
Pressure = force ( in newtons ) / area ( in m^2 )
pressure put
= 30 000 N / 0.75 m^2
= 40 000 Pa
ENGLISH:
It distinguishes between the fermions, which are particles of matter, and the bosons, which carry forces. The matter particles include six quarks and six leptons. The six quarks are called the up, down, charm, strange, top and bottom quark. ... All of these matter particles fall into three “generations.”
SPANISH:
Distingue entre los fermiones, que son partículas de materia, y los bosones, que transportan fuerzas. Las partículas de materia incluyen seis quarks y seis leptones. Los seis quarks se denominan quark arriba, abajo, encanto, extraño, superior e inferior. ... Todas estas partículas de materia se dividen en tres "generaciones".
Electrons are important to the electric current because they are able to move from one atom to another. When an atom loses an electron, it becomes positively charged and when an atom gains an electron, it becomes negatively charged.
