Công thức tính công suất phản kháng động lực

If you were designing a bumper for a car, would you prefer it to exhibit elastic or plastic deformation? why? consider the functions of a bumper in both a minor "fender-bender" and a major collision.

Water vapor initially at 10 bar and 400 °c is contained within a piston-cylinder assembly. the water lost heat to the surrounding according to isochoric (iso-volumetric) process until its temperature is 150 °c. the water is then condensed isothermally to saturated liquid. for the water as a system, calculate the work in kj/kg

Plan an experiment to measure the surface tension of a liquid similar to water. if necessary, review the ncfmf video surface tension for ideas. which method would be most suitable for use in an undergraduate laboratory? what experimental precision could be expected?