Question Number 142992 by otchereabdullai@gmail.com last updated on 08/Jun/21
Commented by otchereabdullai@gmail.com last updated on 08/Jun/21
$$\mathrm{please}\:\mathrm{help}\:\mathrm{me}\:\mathrm{understand}\:\mathrm{why}\:\mathrm{we}\: \\ $$$$\mathrm{have}\:\mathrm{S}=−\mathrm{20m}\:\mathrm{in}\:\mathrm{option}\:\left(\mathrm{b}\right) \\ $$
Commented by Olaf_Thorendsen last updated on 08/Jun/21
$${at}\:{the}\:{beginning}\:{h}\:=\:\mathrm{0}{m} \\ $$$${at}\:{the}\:{end},\:{when}\:{the}\:{stone}\:{hits}\:{the} \\ $$$${ground},\:{h}\:=\:−\mathrm{20}{m}\:{because}\: \\ $$$${the}\:{cliff}\:{is}\:\mathrm{20}{m}\:{high}. \\ $$
Commented by otchereabdullai@gmail.com last updated on 08/Jun/21
$$\mathrm{thank}\:\mathrm{you}\:\mathrm{sir}! \\ $$