Answer:
This is a rather complicated thing to explain so I'll try my best. To put it in simple term the sun has whats called a SOI (sphere of infleunce) and anything inside of this is effected by the gravity of that planet or sun in this case. The earth is inside of this sphere of influence. The earth has a constant velocity that is making it move away from the sun but since it's in the suns SOI the path in which the earth moves is changed in a way that causes it to spin around the sun. The same thing is happening with the moon. I'm not 100% sure on this but I think the reason the moon does not just fly away towards the sun is because it is closer to earth and is more effected by earths SOI. Hope this cleared things up for you.
A scientific model is a claim or a theory that helps explain how a phenomenon works or how it undergoes process. This models provides scientists an understanding of the object or a situation undergoes change and generate certain outcomes or effects.
The answer is A. Uses too much energy.
Answer:
lungs:
The blood first enters the right atrium.
The blood then flows through the tricuspid valve into the right ventricle.
When the heart beats, the ventricle pushes blood through the pulmonic valve into the pulmonary artery.
The pulmonary artery carries blood to the lungs where it “picks up” oxygen.
It then leaves the lungs to return to the heart through the pulmonary vein.
The blood enters the left atrium.
It drops through the mitral valve into the left ventricle.
The left ventricle then pumps blood through the aortic valve and into the aorta. The aorta is the artery that feeds the rest of the body through a system of blood vessels.
Blood returns to the heart from the body via two large blood vessels called the superior vena cava and the inferior vena cava. This blood carries little oxygen, as it is returning from the body where oxygen was used.
The vena cavas pump blood into the right atrium and the cycle begins all over again.
It is only active at a pH of around 2 because that is around the same pH as the gastric juices in the stomach which is where pepsin is used to break down proteins.
