4. A plane accelerates down a runway due to the constant resultant force of
2.7 x 10^6 N. Assume air resistance acting on the plane is a constant
6.8 x 10^4 N, and friction between the wheels and the runway is a constant
8.5 x 10^5 N. If the plane travels 1.4 km down the runway before taking off,
calculate how much work the engines do on the plane to get it up to speed.
