1. Reversible adiabatic process is always Isentropic but the reverse is not always true.
2. Stress is a second order tensor quantity.
3. Steels have higher melting point than cast irons i.e. why they are not used in Casting and cast iron is used.
4. 80% cost of Gears is due to making of its complex teeth profile.
5. A beam with no bending moment and pure shear force is possible.