What is the least possible error encountered when taking measurement with a metre rule?

At absolute zero temperature, the average velocity of the molecules 

Calculate the quantity of heat for copper rod whose thermal capacity is 400Jk\(^{-1}\) for a temperature change of 60ºC to  80ºC

When a cell of e.m.f 3.06V is connected, the balance of a potentiometer is 75cm, Calculate the new balance of a cell of e.m.f  2.295V

A body is whirled in a horizontal circle at the rate of 800 revolutions per minute. Determine the angular velocity