Engineering approach

sometimes calculations are really complex and to be unable to settle or sometimes only complex because of this reasons engineers developed a idea which named as engineering approach.According to engineering approach for example if you calculate heat transfer of patato you have to neglect somethings or you have to accept patato is a water because waters heat transfer rate can be easily calculated than patato and calculated values approximately patatos heat transfer rate if we want to shorten time of calculation or avoid calculation errors we have to use engineering approach but we have to use factor of safety for accidental stuations.