Explain how machines can be useful if the output work is always less than the input work

The two required components for a generator

Individuals who live below the poverty line get seriously ill more often than those who do not what could be the hidden variable in this situation?

Asolid round steel rod 6.25 mm in diameter and 375 mm long is rigidly bonded to the end of solid square brass rod 25 mm on a side and 300 mm long. the geometric axes of the bare are along the same line. an axial tensile force of 5.4 kn is applied at the extreme ends of the assembly. for steel e = 200 gpa and for brass e = 90 gpa. determine the total elongation for the assembly.