1. What thickness of concrete (density 2200 kg m-3) is needed to attenuate a collimated beam of 1-MeV γ rays by a factor of 106? The mass attenuation coefficient of concrete μm = 0-064cm2g-1.
2. A Schleiren photo of the flow around a corner reveals the edges of the expansion fan to be indicated by the angles shown in Figure 1. Assume that γ = 1.4.
(a) Determine the Mach number before and after the corner.
(b) Through what angle was the flow turned, and what is the angle of the expansion fan (θ3)?
3. A smooth concave turn similar to that shown in Figure 1 turns the flow through a 30° angle. The fluid is oxygen and it approaches the turn at M1 = 4.0.
(a) Compute M2, T2/ T1, and p2/pi via the Prandtl-Meyer compression which occurs close to the wall.
(b) Compute M2', T2'/ T,, and p2'/P1 via the oblique shock that forms away from the wall. Assume that this flow is also deflected by 30°.
(c) Draw a T-s diagram showing each process.
(d) Can these two regions coexist next to one another?
Figure 1