Strongest beyblade in the world

If the thermal strain developed in polyimide film during deposition is given as 0.0044. assume room temperature is kept at 17.3 c, and thermal coefficient of expansion for the film and the substrate are 54 x 10^-6c^-1 and 3.3 x 10^-6c^-1respectively. calculate the deposition temperature.

Coiled springs ought to be very strong and stiff. si3n4 is a strong, stiff material. would you select this material for a spring? explain.

The higher the astm grain-size number, the coarser the grain is. a)-true b)-false