Question Number 24685 by Tinkutara last updated on 24/Nov/17
$$\mathrm{The}\:\mathrm{sum}\:\mathrm{of}\:\mathrm{the}\:\mathrm{kinetic}\:\mathrm{and}\:\mathrm{potential} \\ $$$$\mathrm{energies}\:\mathrm{of}\:\mathrm{a}\:\mathrm{system}\:\mathrm{of}\:\mathrm{objects}\:\mathrm{is}\:\mathrm{conserved} \\ $$$$\left(\mathrm{1}\right)\:\mathrm{Only}\:\mathrm{when}\:\mathrm{no}\:\mathrm{external}\:\mathrm{force}\:\mathrm{acts}\:\mathrm{on} \\ $$$$\mathrm{the}\:\mathrm{objects} \\ $$$$\left(\mathrm{2}\right)\:\mathrm{Only}\:\mathrm{when}\:\mathrm{the}\:\mathrm{objects}\:\mathrm{move}\:\mathrm{along} \\ $$$$\mathrm{closed}\:\mathrm{paths} \\ $$$$\left(\mathrm{3}\right)\:\mathrm{Only}\:\mathrm{when}\:\mathrm{the}\:\mathrm{work}\:\mathrm{done}\:\mathrm{by}\:\mathrm{the} \\ $$$$\mathrm{resultant}\:\mathrm{external}\:\mathrm{force}\:\mathrm{is}\:\mathrm{zero} \\ $$$$\left(\mathrm{4}\right)\:\mathrm{None}\:\mathrm{of}\:\mathrm{these} \\ $$
Commented by ajfour last updated on 25/Nov/17
$$\left(\mathrm{3}\right).\:\:\:\left(?\right) \\ $$
Commented by Tinkutara last updated on 25/Nov/17
$$\mathrm{No}. \\ $$
Commented by ajfour last updated on 25/Nov/17
$${Any}\:{explanation}\:{to}\:{back}\:{up}\:? \\ $$