Question Number 136105 by I want to learn more last updated on 18/Mar/21
Commented by mr W last updated on 18/Mar/21
$${book}\:{is}\:{wrong}! \\ $$$${just}\:{think}:\:{can}\:{a}\:{man}\:{throw}\:{a}\:{stone} \\ $$$$\mathrm{177}\:{m}\:{till}\:\mathrm{420}\:{m}\:{high}?\:{even}\:{not}\:{a} \\ $$$${cannon}\:{can},\:{i}\:{think}! \\ $$
Commented by I want to learn more last updated on 18/Mar/21
$$\mathrm{Thanks}\:\mathrm{sir}. \\ $$$$\mathrm{I}\:\mathrm{used}:\:\:\:\:\:\mathrm{v}^{\mathrm{2}} \:\:\:=\:\:\:\mathrm{u}^{\mathrm{2}} \:\:−\:\:\mathrm{2gh},\:\:\:\:\:\:\:\:\mathrm{0}\:\:\:=\:\:\:\mathrm{u}^{\mathrm{2}} \:\:\:−\:\:\mathrm{2gh} \\ $$$$\mathrm{I}\:\mathrm{used}\:\:\:\:\:\:\mathrm{H}\:\:\:=\:\:\:\:\frac{\mathrm{u}^{\mathrm{2}} }{\mathrm{2g}}\:\:\:=\:\:\:\frac{\mathrm{8}^{\mathrm{2}} }{\mathrm{20}}\:\:\:=\:\:\:\frac{\mathrm{64}}{\mathrm{20}}\:\:\:=\:\:\:\mathrm{3}.\mathrm{2}\boldsymbol{\mathrm{m}} \\ $$$$\mathrm{Am}\:\mathrm{i}\:\mathrm{right}? \\ $$
Commented by mr W last updated on 18/Mar/21
$${clear}! \\ $$
Commented by I want to learn more last updated on 19/Mar/21
$$\mathrm{Thanks}\:\mathrm{sir},\:\mathrm{i}\:\mathrm{appreciate}.\:\mathrm{Am}\:\mathrm{happy}\:\mathrm{i}\:\mathrm{got}\:\mathrm{it}.\:\mathrm{Thanks}\:\mathrm{for}\:\mathrm{your}\:\mathrm{help}\:\mathrm{sir} \\ $$