Our bodies conduct physics every second of everyday. Our bodies pump blood. Initially, one may think that the mere action of pumping blood has no correlation with physics at all. On the contrary, the blood in our bodies must be pumped through muscle contraction and applied force as well as pressure. Last year in physics B, we learned quite a bit about fluid mechanics and the relationship between force, pressure and area of the tube the fluids travel through. As our heart initially pumps blood from the heart, it travels through the arteries in the downward direction towards the lower part of our bodies. Not as much energy and force needs to be applied because gravity provides a lot of the force needed to carry the blood through the arteries through the body. That is why the arteries are larger and do not apply as much pressure and force as the veins do. Veins are the other muscular passage way that carries blood but it carries blood back to the heart to be replenished with oxygen. The veins need to carry the blood from the bottom of the human body, against the pull of gravity, towards the heart. Therefore, in order to successfully transfer the blood to the heart, a force greater in magnitude than the force of gravity needs to be applied. F=(P/A) This relationship shows that a smaller area will increase the applied force. The contractions of the veins provide the required pressure and the smaller radius of the veins compared to that of the arteries creates a greater force. That force overcomes the force of gravity so the blood can be constantly circulated within the human body.