An hover craft vehicle operates by moving atmospheric air ( = 1.22 kg/m3 ) with a large fan through the skirt of the vehicle which creates a 3 cm clearance with the ground. If the vehicle weighs 50 kN find a) the required air volumetric flow rate and b) the fan power. (30.6 m3 /s, 54 kW)

A.

Explanation:

For example,

If you start from 0 and move 5 units in the positive x axis and reverse to return to 2 units from 0, your displacement will be 2 units but distance covered will be 8 units.

Average velocity = Displacement / time

= 2 / time

Average speed = distance / time

= 8 / time

Here, time will be the same, so you can see that magnitude of the average velocity of a particle moving in one dimension smaller than the average speed over some time interval.