A mole of iron is therefore 55.845 grams. Quick conversion of 1 cubic foot to liters gives us 28.32 liters. Going back we can take this number to find that 28.32 liters of gas at STP is going to be 1.26414494 moles of air. Great, we can now determine how many moles of each particular substance we have from the percentage composition of air.
X-rays are attenuated as they pass through matter. That is, the intensity of an X-ray beam decreases the farther it penetrates into matter. Basically, each interaction of an X-ray photon with an atom of the material removes an X-ray from the beam, decreasing its intensity.
In order to investigate the effects of the speed and length of train on the attenuation characteristics, the variations in vibration amplitude with distance are plotted in Fig. 8for two cases: (i) a saemaul express train of 8 cars with a speed of 135 km/h; and (ii) a freight train of 24 cars with a speed of 71 km/h.