Where does the heating process begin in a hot water heater system?

-- The pipes don't do any heating; they just carry stuff from one place to another.

-- The radiator's job is to LOSE heat ... it RADIATES heat from the hot fluid in the pipes out to the room that needs to be heated.

-- The BOILER is the place where you BOIL something, usually water, (using coal, oil, natural gas, radioactive Uranium, or electricity).  Then you push it THROUGH the pipes TO the radiator, where the heat it's carrying can shine out into the cold room and warm things up.  

because growing process had stoped after 4-5 year

490 n

f=125n a=2.5m/s2