Question 12: Why a car has oblong shape?
When a body moves in a fluid (like air), there is always a resistance to the motion of the body. This resistance is dependent mostly upon the viscosity of the fluid and design (shape) of the moving body.
When a car is moving, it is like a body moving in the fluid (air). So it is important to design the shape of the car such that it experiences minimum resistance or drag from the air.
The oblong shape of the car reduces the turbulence by streamlining the fluid. Therefore, less resistance is offered by the air and the car moves faster with less expenditure of the fuel.