Air flows from a reservoir in which the pressure is kept at 124 kPa through a convergent–divergent nozzle and exhausts to the atmosphere where the pressure is 101.3 kPa. Under these conditions, the nozzle is choked and the flow is subsonic on both sides of the throat. To what value must the pressure in the reservoir be increased so that there is a normal shock on the nozzle exit plane?

Describe one experiment in which the glass transition temperature and melting temperature of a totally amorphous thermoplastic material can be determined. show the relevant experimental results in a diagram which should be properly annotated with the two temperatures clearly marked. what is likely to happen to the curve in the diagram if the amorphous polymer is replaced by a thermosetting type?