When an airplane takes off it sheds a starting vortex. We have been using a horseshoe vortex model for the finite wing, but a square closed loop might be more realistic. Estimate the downwash velocity induced at the center of the wing by the starting vortex for a small plane (mass 1000 kg, wingspan 11 m, speed at takeoff 25m/s) for a distance from the starting vortex to the wing of 10 m, 100 m, and 1000 m. Comment on the magnitude of the effect. Assume standard atmospheric conditions and neglect the ground effect.

Explanation:

The mass of a body is a measure of its inertia. It means larger the mass of a body, larger will be the inertia offered by the body to change its state of motion. The following examples will clarify the concept:

Examples;

When we kick a football, it flies a long way but at the same time if we kick a stone of the same size, it hardly moves, as the stone resists a change in its motion better than the football because of its more mass.

We can increase the velocity of our bicycle by pedaling harder, i.e., on applying more force. But the same force will produce a negligible change in the motion of a bus, because in comparison to the bicycle, a bus has more tendency to oppose any change in its state of motion because of its larger mass i.e., the bus has more inertia than the bicycle.

The SI unit of mass and inertia is kilogram (kg).