Consider a subsonic engine inlet (i. e., a diffuser) with an inlet area of 1.5 m2 and exit-to-inlet area ratio of 1.44. Air enters the diffuser flowing at 5 kg/s with a static pressure of 0.350 bar and a velocity of 110 m/s. The gases exit the diffuser at a static pressure of 0.375 bar and a velocity of 80 m/s. Assume that the ambient (external) pressure on the walls of the diffuser is 0.340 bar. a.) For these conditions, what is the force (in units of lbf and N) transmitted to the structure
holding the diffuser? Provide both direction and magnitude of the force, and use a
picture to help present your answer.
b.) Based solely on your results, comment on whether the force acting on the diffuser would
help speed up or slow down a vehicle that used this diffuser as part of a jet propulsion
system.

Ai=2300 in2 , Ao=Ai*1.44=3312 in2

m=10 lbm/s

Pi=5 psia , Po=5.4 psia , Pa=5.5 psia

Vi=120 m/s , Vo=78 m/s

a) Force =m(Vo-Vi) = -190.5 N = -42.82 lbf (towards the inlet)

b) since force is negative it will slow down the system.

answer: the correct answer is 1.

explanation: there are various process in which a radioactive nuclei decays:

1) alpha decay: in this process, a heavier nuclei decays into lighter nuclei by releasing alpha particle. the mass number is reduced by 4 units.

2) electron capture: in this decay process, a parent nuclei absorbs an electron and gets converted into a neutron. simply, a proton and an electron combines together to form a neutron. mass number does not change in this process.

3) gamma ray emission: it is a decay process in which an unstable nuclei gives excess energy by a spontaneous electromagnetic process. this decay releases . this process does not change the mass number.

4) positron emission: it is a type of decay process, in which a proton gets converted to neutron and an electron neutrino. this is also known as -decay. in this the mass number remains same.

from the above information, we see that only alpha-decay is producing a change in the mass number of the nucleus.