Question Number 10736 by Saham last updated on 23/Feb/17
$$\mathrm{A}\:\mathrm{tennis}\:\mathrm{ball}\:\mathrm{is}\:\mathrm{thrown}\:\mathrm{vertically}\:\mathrm{upward}\:\mathrm{with}\:\mathrm{an}\:\mathrm{initial}\:\mathrm{velocity}\:\mathrm{of} \\ $$$$\mathrm{50m}/\mathrm{s},\:\mathrm{when}\:\mathrm{the}\:\mathrm{ball}\:\mathrm{return}\:\mathrm{to}\:\mathrm{the}\:\mathrm{point}\:\mathrm{of}\:\mathrm{projection}\:\mathrm{it}\:\mathrm{renounce}\: \\ $$$$\mathrm{with}\:\mathrm{the}\:\mathrm{velocity}\:\mathrm{of}\:\:\frac{\mathrm{2}}{\mathrm{3}}\:\mathrm{of}\:\mathrm{the}\:\mathrm{velocity}.\:\mathrm{Calculate}\:\mathrm{the}\:\mathrm{heigth}\:\mathrm{after}\:\mathrm{renounce}. \\ $$
Answered by mrW1 last updated on 24/Feb/17
$$\frac{\mathrm{1}}{\mathrm{2}}{mV}_{\mathrm{2}} ^{\mathrm{2}} ={mgh} \\ $$$$\Rightarrow{h}=\frac{{V}_{\mathrm{2}} ^{\mathrm{2}} }{\mathrm{2}{g}}=\frac{\left(\frac{\mathrm{2}}{\mathrm{3}}×\mathrm{50}\right)^{\mathrm{2}} }{\mathrm{2}×\mathrm{9}.\mathrm{81}}=\mathrm{56}.\mathrm{6}\:{m} \\ $$
Commented by Saham last updated on 24/Feb/17
$$\mathrm{God}\:\mathrm{bless}\:\mathrm{you}\:\mathrm{sir}. \\ $$
Commented by chux last updated on 25/Feb/17
$$\mathrm{please}\:\mathrm{mrw1}\:\mathrm{are}\:\mathrm{you}\:\mathrm{also}\:\mathrm{known}\:\mathrm{as} \\ $$$$\mathrm{Ise} \\ $$
Commented by mrW1 last updated on 25/Feb/17
$${no}.\:{an}\:{other}\:{id}\:{i}\:{have}\:{used}\:{is}\:{mrW}. \\ $$
Commented by chux last updated on 25/Feb/17
$$\mathrm{ok}\:\mathrm{sir} \\ $$