To answer this question, we have to look into our atmosphere. It’s full of air isn’t it? Aeroplanes utilizes this presence of air in the atmosphere to fly. The branch of Physics that deals with this is known as aerodynamics. The specially designed shape of the aeroplane is the primary answer to this question. This special design enables aeroplane to get necessary thrust from the atmosphere to raise, glide and to stay in air. If we take a closer look we can understand that the shape is similar to that of eagles. The wings of the aeroplane is designed in a special way such that the upper part is curved and the lower part is somewhat flat. It is in this point Bernoulli’s principle comes to action. Bernoulli’s principle states that the pressure exerted by a moving fluid is inversely proportional to the speed of the fluid. In other words, fluid pressure decreases as fluid speed increases, and vice versa. This same applies to gas also. The movement of air across the wings create an upward force which is greater than the gravitational force exerted by the earth. The faster that air moves through a space, the lower the air pressure; the slower it moves, the higher the pressure. The air moving over the top of the wings is faster than the air going underneath. This leads to the formation of low pressure on the top of the wings. As usual air moves from high pressure to low pressure region and this creates an upward thrust enable the aeroplane to overcome the gravitational force exerted by the earth.