What is a windmill? With the help of a diagram,describe in brief the construction and working of a windmill. Give uses of wind energy.

(N/A) windmill is a machine that works using the energy of blowing wind. It can be used to run water pumps (to draw water from the ground) and also for grinding grains.
Construction: It consists of a circular wheel to which blades are attached radially to catch the wind. The center of this circular wheel is connected to one end of a crank rod. The $U$-bend of the crank is connected to the pump rod (piston rod).
Working: When the blowing wind strikes the blades of a windmill,the $KE$ (Kinetic Energy) of the wind rotates the blades continuously,which in turn rotates the attached crank. As the crank rotates,its $U$-bend lifts the pump rod up and down continuously. This pump rod operates the pump,which lifts the underground water.
Uses of wind energy:
$(i)$ Wind energy is used to propel sail boats to transport men and materials from one place to another.
$(ii)$ Wind energy is used to run water pumps to draw out underground water.
$(iii)$ Wind energy is used to run flour-mills to grind the grains.
$(iv)$ Wind energy is used to generate electricity.