In nuclear physics, the energy of a subatomic article can be measured in various ways. One way is to measure how quickly the particle is stopped by an obstacle such as a piece of lead and then to use published graphs of energy versus stopping rate. Figure 3.7 shows such a graph for photons (the particles of light) in lead. The vertical axis shows the photons' energy E in MeV (millions of electron volts), and the horizontal axis shows the corresponding absorption coefficient p, in cm2/g. (The precise definition of this coefficient need not concern us here;µ is simply a suitable measure of how quickly the photon is stopped in the lead.) From this graph, you can obviously find the energy E of a photon as soon as you know its absorption coefficient A. (a) A student observes a beam of photons (all with the same energy, E) and finds that their absorption coefficient in lead is A = 0.10 ± 0.01 cm2/gram. Using the graph, find the energy E and the uncertainty 8E. (You may find it helpful to draw on the graph the lines connecting the various points of interest, as done in Figure 3.3.) (b) What answer would the student have found if he had measured = 0.22 ± 0.01 cm2/gram?