Why is weight measured in newtons

Arod of some material 0.20 m long elongates 0.20 mm on heating from 21 to 120°c. determine the value of the linear coefficient of thermal expansion [in (degrees c)^-1] for this material.

Which one of the following research methods can show cause and effect

Mechanical energy is when the amount of kinetic and potential energies added together remains the same. conserved created lost