Step-by-step explanation:
It is given that,
Distance covered by the airplane,
![d=8.72\ km=8.72* 10^3\ m](https://img.qammunity.org/2020/formulas/physics/college/od885885vftu8943991erne3eb3xgt28iu.png)
Time taken, t = 35.9 s
Acceleration of the airplane,
![a=3.03\ m/s^2](https://img.qammunity.org/2020/formulas/physics/college/3ajk4auyyko4vjqtro20c9bsvfg88xeylp.png)
(a) Let u is the initial speed of the airplane at the beginning of the 35.9 seconds. It can be calculated using the second equation of motion as :
![d=ut+(1)/(2)at^2](https://img.qammunity.org/2020/formulas/physics/college/cnmnl56g8a1pmreipfvlacntz8hqzm02l7.png)
![u=(d-((1)/(2)at^2))/(t)](https://img.qammunity.org/2020/formulas/physics/college/qb9pl6uhoi84ozuz4h0ob67v336i8bb5gk.png)
![u=(8.72* 10^3-((1)/(2)* 3.03* (35.9)^2))/(35.9)](https://img.qammunity.org/2020/formulas/physics/college/c5s64ek6g7eae2h6ze1g8er0twq8bkxf1n.png)
u = 188.50 m/s
(b) Let v is the speed of the airplane at the end of the 35.9 seconds. It can be calculated using the first equation of motion as :
![v=u+at](https://img.qammunity.org/2020/formulas/physics/middle-school/8u69t2dm31jy4f6e8h3i9msisjzkrvuvq4.png)
![v=188.50+3.03* 35.9](https://img.qammunity.org/2020/formulas/physics/college/8tc1hlif8prdmut7cyzzx0325dme8tpg0o.png)
v = 297.27 m/s
Hence, this is the required solution.