One method of getting a tight fit, say of a metal peg in a hole in a metal block, is to manufacture the peg slightly larger than the hole. The peg is then inserted when at a different temperature than the block. Should the block be hotter or colder than the peg during insertion? Explain your answer.
The metal block should be colder than the peg. Since the metal peg is made larger, therefore the temperature of the metal block should be less than the temperature of the peg so that if peg is inserted into the hole and temperature rises, it gets a tight fit due to thermal expansion of the metal block.
The size of the hole reduces due to thermal expansion of metal when temperature rises. Therefore, at the insertion time the temperature of the metal block should be less than the temperature of peg.