a How long would it take a 150 105 kg airplane with engines

(a) How long would it take a 1.50 10⁵ kg airplane with engines that produce a maximum of 100 MW of power to reach a speed of 250 m/s and an altitude of 12.0 km if air resistance were negligible?
s
(b) If it actually takes 875 s, what is the power applied, in megawatts?
MW
(c) Given this power, what is the average force of air resistance if the airplane takes 1200 s? (Hint: You must find the distance the plane travels in 1200 s assuming constant acceleration.)
kN

Please help show steps.

Solution

(a)

the time is calculated as follows:

t = [0.5mv² + mgh ] / P = [0.5 *1.50 10⁵*250*250 +(1.50 10⁵ * 9.8 *12000)] / 100X10⁶ = 223.275 s

(b)

P= [0.5mv² + mgh ] / t = [0.5 *1.50 10⁵*250*250 +(1.50 10⁵ * 9.8 *12000)] / 875 = 25.5 MW

(c)

Use the equation, v = u + at and find a.

use the equation s = 0.5at2 and find distance d.

Hence, the required force is,

F = Energy / distance = P * time / distnce = [25.5x10⁶ * 1200] / 150000 = 2.04e+5 N = 204 kN