Answer
$(a)\space 162.8\space MW$
$(b)\space 276.8\space MW$
Work Step by Step
(a) We know 1 km=1000 m & we can multiply the speed by 1000 m/km & use the 1h/3600s conversion factor to convert the units of aircraft speed as follows.
$913\space km/h= (\frac{913\space km}{h})(\frac{1000\space m}{km})(\frac{h}{3600s})=253.6\space m/s$
Let's apply the equation $P=FV$ to aircraft to find the engine power.
$P=FV$ ; Let's plug known values into this equation.
$P= 642\space kN\times 253.6\space m/s= 642\times10^{3}\times 253.6\space m/s$
$P=162.8\space MW$
(b) Please see the attached image first.
We know 1 km=1000 m & we can multiply the speed by 1000 m/km & use the 1h/3600s conversion factor to convert the units of aircraft speed as follows.
$622\space km/h= (\frac{622\space km}{h})(\frac{1000\space m}{km})(\frac{h}{3600s})=172.8\space m/s$
We can find the drag force (air resistance) using (a), it's equal to the engine thrust force
$F_{Drag}=642\space kN$
We can find the applied engine thrust force when climbing $23^{\circ}$ angle through air as follows.
$F=F_{Drag}+245\times10^{3}gsin23^{\circ}$
$F=642\times10^{3}\space N+245\times10^{3}\times9.8\space N\times0.4$
$F=1602.3\space kN$
Let's apply the equation $P=FV$ to aircraft to find the engine power.
$P=FV$ ; Let's plug known values into this equation.
$P= 1602.4\space kN\times 172.8\space m/s= 1602.4\times10^{3}\space N\times 253.6\space m/s$
$P=276.8\space MW$
