You can measure this rate by walking barefoot from carpeting to hardwood to tile flooring. The temperatures will all be the same, but will seem very different. The tile has the highest rate and will seem the coldest, while the carpeting has the lowest rate and will seem the warmest. The greater the difference, the higher the speed. A temperature difference of 40 degrees is twice as fast as a temperature difference of 20 degrees.
Insulation is resistance.
It resists the pressure of the temperature's wind. It slows the wind down. R-value is the measurement of a material's ability to slow the temperature's wind. The higher the r-value, the slower the wind speed thru that substance. It takes the wind twice as long to penetrate a R20 as an R10.