An iron rod with diameter of 12cm
at 20°c is to be fixed into a steel
plate having
a hole
of
diameter 10cm
at same temperature.
To what Temperature must the steel
plate be heated in order for the
for
rod to Fix ?
[linear expansivity of the steel is 0.00001/K]​

Neptune is the eighth planet from the sun. it was the first planet to get its existence predicted by  mathematical calculations  before it was actually seen through a telescope on sept. 23, 1846. irregularities in the orbit of  uranus  led french astronomer alexis bouvard to suggest that the gravitational pull from another celestial body might be responsible. german astronomer johann galle then relied on subsequent calculations to   spot neptune via telescope. previously, astronomer galileo galilei sketched the planet, but he mistook it for a star due to its slow motion. in accordance with all the other planets seen in the sky, this new world was given a name from greek and roman mythology — neptune, the roman god of the sea.

Protons have a positive charge and, collectively, give an element its atomic number.

Scientific classification