Educating Engineerings

What happens here ..explain plz.
Why it happened??
Follow plz.....

comment your view plz..
follow plz...

sandblasting..Sandblasting is the act of propelling very fine particles of an abrasive material at high velocity toward a surface in order to clean or etch it. Sandblasting is often used as a way to prepare a surface prior to painting. It is commonly used to strip paint from machinery and metal, but it has many other uses as well...

automatic solar cleaner..
follow plz...

Reason plz..
follow plz...