Answer:
There's no short answer.
Explanation:
The engines start working by burning fuel, this in turn starts turning the engine blades and the blades suck in air and push it out from the back of the engines. This creates a force that pushes the airplane forward. As the volume of air that goes in and out of the engines increase, so does the kinetic energy the airplane has. At a specific speed, depending a lot of factors such as the weight of the airplane, the length of the wings etc, the force that the moving air provides from beneath the wings surpasses the force of gravity that is applied to the plane, the plane takes off.
I hope this answer helps.
