Why is it important to study and understand the behavior of materials when forces are applied to them?

Answer 1

There can be various answers to this question depending on what you imagine these materials will be used for. Suppose you were building a dam and could not accurately tell what the effects of billions of tons of water constantly pressing and churning against the dam would be, the dam would likely collapse. Suppose the manufacturer fo you car's engine did not know the effects of millions of explosions of vaporised gasoline in the piston chambers would have on the engine block, your engine might shake itself apart very quickly. When the Hubble Space Telescope was first launched, the designers had miscalculated the thermal effects on the solar panels of constantly passing from light to dark in the vacuum of space. The thermal expansion and contraction that occurred during every orbit was gradually shaking the original solar panels apart. Thus we had to replace them with new, better designed ones on the first serviceing mission.