Measuring the thermal diffusivity of bearing balls. The company mentioned in the problem above wants to measure the thermal diffusivity of bearing balls made from a special alloy after heat treatment and quenching. Their approach involves drilling a very small hole that reaches to the center of the ball and inserting a fine thermocouple as shown below. This assembly is then quickly put in a convection oven. The response time and the thermal mass of the thermocouple are insignificant. A set of temperature measurements at the center of a bearing ball is given in the supplementary Excel sheet (see ODTClass). The temperature of the oven was 150C and the initial temperature of the bearing ball was 20 C. Use the data and estimate the thermal diffusivity with a graphical method, utilizing as many data points as you can