Lift
To overcome the weight force a plane needs to generate the opposing force lift. Lift is a mechanical aerodynamic (air and motion) force which is generated when a solid object (the plane) moves through a fluid (air.) For lift to be generated the fluid needs to be deflected by the solid object. Lift is generated by the difference in velocity between the solid and the fluid.
When a plane moves forward the wing (solid) splits the airflow of the fluid into two directions: over the wing and under the wing. The wing or airfoil is shaped so that the air moving over the top moves at a higher velocity than the air moving under the underneath. Bernoulli’s principle explains how this helps to generate lift. Bernoulli’s principle is as according to infoplease.com "physical principle formulated by Daniel Bernoulli that states that as the speed of a moving fluid (liquid or gas) increases, the pressure within the fluid decreases." Therefore, the upper streamline in figure 2 below has a lower pressure as the air particles are moving at a higher velocity and the lower streamline has a higher pressure as the particles are moving at a lower velocity. It is this differential pressure between the top and bottom of the wing which creates a force which lifts the plane into the air. The higher pressure air of the lower side of the plane directs air downwards which in turn pushes the plane upwards in accordance with Newton’s third law of motion. This is evident in figure 2.
When a plane moves forward the wing (solid) splits the airflow of the fluid into two directions: over the wing and under the wing. The wing or airfoil is shaped so that the air moving over the top moves at a higher velocity than the air moving under the underneath. Bernoulli’s principle explains how this helps to generate lift. Bernoulli’s principle is as according to infoplease.com "physical principle formulated by Daniel Bernoulli that states that as the speed of a moving fluid (liquid or gas) increases, the pressure within the fluid decreases." Therefore, the upper streamline in figure 2 below has a lower pressure as the air particles are moving at a higher velocity and the lower streamline has a higher pressure as the particles are moving at a lower velocity. It is this differential pressure between the top and bottom of the wing which creates a force which lifts the plane into the air. The higher pressure air of the lower side of the plane directs air downwards which in turn pushes the plane upwards in accordance with Newton’s third law of motion. This is evident in figure 2.
Figure 2- Production of Lift
When an airplane moves forward and generate more lift than weight the lift pushes the plane up and it flies. In mid-flight the forces of weight and lift are equal so the net force is zero and the plane stays in the air. The greater the velocity of a plane the greater the lift. For further reading on this principle click here.