Note that a turbojet engine produces forward thrust when operating in a normal man$-$

ner, but it can produce reverse thrust if the exhaust jet is deflected by a "thrust

reverser", which is used in particular when the aircraft is landing. Suppose that while

the aircraft rolls down the runway at a speed of $150k\frac{m}{h}r,$ the idling engine consumes

air at $50k\frac{g}{sec}$ and produces an exhaust velocity of $150\frac{m}{sec}.$ The inlet and exhaust

pressures are the same, and in this problem one can neglect the mass flow rate of fuel.

a$)$ What is the forward thrust of this engine during standard operation while landing,

without any thrust reverser?

b$)$ What are the magnitude and direction $($i$.$e$.,$ forward or reverse, in the positive or

negative $x-$direction, respectively$)$ of the net thrust if the flow from the exhaust

is deflected by $90,$ without affecting the mass flow? A common geometry for a

thrust reverser to achieve this is shown in the sketch below. In this problem, the

stated $90$ deflection would correspond to the angle $=0$ in the sketch.

c$)$ What are the magnitude and direction of the thrust $($forward or reverse$)$ after

the plane has come to a stop, with the thrust reverser operating such that

$=0$ and with an inlet airflow rate of $40k\frac{g}{sec?}$