Question

An airline executive decides to economize by reducing the amount of fuel required for long-distance flights. He orders the ground crew to remove the paint from the outer surface of each plane. The paint removed from a single plane has a mass of approximately 100 kg. (a) If the airplane cruises at an altitude of 12000 m, how much energy is saved in not having to lift the paint to that altitude? (b) How much energy is saved by not having to move that amount of paint from rest to a cruising speed of 250 m/s?

Answer 1

Answer

given,                                                          

mass of paint removed from the airline = 100 Kg

a) altitude of the airplane = 12000 m

  energy saved to not to lift the plane = ?

              U = m g h                              

              U = 100 x 9.8 x 12000              

              U = 117.6 x 10⁵ J                  

              U = 1.18 x 10⁷ J                  

b) Speed of the airplane = 250 m/s                

              $U = \dfrac{1}{2}mv^2$                                  

              $U = \dfrac{1}{2}\times 100 \times 250^2$

              U =31.25 x 10⁵ J                                              

              U = 3.125 x 10⁶ J