Air flows through a duct of constant cross-sectional area a=0.1m2 . at a certain point ‘x’ in the duct, the pressure is measured at 1.5 bar, the temperature is 100°c, and the air velocity is 100 m/s. at another point ‘y’, the pressure has dropped to 1.4 bar, and the velocity of the air is now 171.4 m/s. you may assume that the flow is frictionless.
1. using the data recorded at point x, calculate the mass flowrate of air in the duct
2. calculate the temperature at point y
3. write the steady flow energy equation out in full, and then simplify it to calculate the heat added to the air between points x and y

A1,200 kg car is accelerated at 3.7 m/s2. what force was needed to produce this acceleration? a. 4,440 n b. 324.3 n c. 4,388 n d. 304.3 n

Some material consisting of a collection of microscopic objects is kept at a high temperature. a photon detector capable of detecting photon energies from infrared through ultraviolet observes photons emitted with energies of 0.3 ev, 0.5 ev, 0.8 ev, 2.0ev, 2.5ev, and 2.8ev. these are the only photon energies observed. (a) draw and label a possible energy-level diagram for one of the microscopic objects, which has four bound states. on the diagram, indicate the transitions corresponding to the emitted photons. explain briefly. (b) would a spring–mass model be a good model for these microscopic objects? why or why not? (c) the material is now cooled down to a very low temperature, and the photon detector stops detecting photon emissions. next, a beam of light with a continuous range of energies from infrared through ultraviolet shines on the material, and the photon detector observes the beam of light after it passes through the material. what photon energies in this beam of light are observed to be significantly reduced in intensity (“dark absorption lines”)? explain briefly.

A17,250 kg rocket is pushed with a thrust of 6,450,284 n. what is the acceleration of the rocket?