Why during a linear thermal expansion do we have to wait for the rod to reach a uniform temperature record the change in length and measure again several changes in length upon cooling.

Question

abmon98 · Answer

Why cant we just measure changes in length as temperature rises from 10-20 then from 20-30 and so on?

anonymous · Answer

Hey.
Of course for a better precision and accuracy you will need to measure a quantity a considerable number of times.
given that we are talking about linear expansion, we have to ensure that at relatively small interval of temperatures, we roughly have to expect the trend of a constant change in length. Thus you will need to measure at such short intervals.
Plus measuring the rod while not in uniform temperature, the rate of change of temperature at a particular point on rod will be different from any other point. When you try to measure the same point again, it might be not at the same uniform temperature as before, leaving your conclusion far from accurate.

abmon98 · Answer

I am not arguing about the number of measurement I should take. Why When started heating the rod for every 5 degrees of increase in temperature for instance measured the corresponding change in length by reading the rise on the dial micrometer

abmon98 · Answer

sorry the change in length on the dial micrometer*

anonymous · Answer

You will need  a constant interval of temperature to make sure it is proportional to the change in length as well.