A hydraulic bottle jack has a small piston of diameter 25 mm and a large piston of diameter 125 mm. A student claims that pressing with 400 N will always lift a 10 kN car because the area ratio is 25. The physics teacher disagrees.
(i) Explain qualitatively why the student’s statement is incomplete, even though the numerical area ratio seems to permit such a load.
(ii) Describe how limitations on maximum allowable fluid pressure and material strength of the pistons affect the actual load that can be safely lifted.
(iii) Suggest any two design changes—other than increasing the operator’s force—that could raise the jack’s load capacity, and justify each suggestion in one or two sentences.