Question Number 178582 by Best1 last updated on 19/Oct/22
$${show}\:{that}\:{Range}\:{of}\:{the}\:{ff}\:{projection}\: \\ $$$${obtained}\:{by}\:{algebric}\:{expression} \\ $$$${R}=\frac{\left({ucos}\theta\right)\left({usin}\theta\right)+\sqrt{\left({usin}\theta\right)^{\mathrm{2}} +\mathrm{2}{gh}}}{{g}}\:\:\:{help}\:{me}\:{please} \\ $$
Commented by Best1 last updated on 18/Oct/22
$${please}\:{help}\:{me} \\ $$
Commented by Ar Brandon last updated on 18/Oct/22
$$\mathrm{dimension}\:\mathrm{of}\:\left(\mathrm{sin}\theta^{\mathrm{2}} \right)\neq\mathrm{dimension}\:\mathrm{of}\:\mathrm{2}{gh}={M}^{\mathrm{2}} {T}^{−\mathrm{2}} \\ $$$$\mathrm{Check}\:\mathrm{question}. \\ $$
Commented by Best1 last updated on 19/Oct/22
$${i}\:{corrected}\:{it}\:{now}\:{help}\:{me} \\ $$
Answered by Ar Brandon last updated on 18/Oct/22
$$\mathrm{For}\:\mathrm{horizontal}\:\mathrm{displacement} \\ $$$${u}_{{x}} ={u}\mathrm{cos}\theta\:\Rightarrow{x}={u}_{{x}} {t} \\ $$$$\Rightarrow{R}=\left({u}\mathrm{cos}\theta\right){t}\:\Rightarrow{t}=\frac{{R}}{{u}\mathrm{cos}\theta}\:…\left({i}\right) \\ $$$$\mathrm{For}\:\mathrm{vertical}\:\mathrm{displacement} \\ $$$${y}={u}_{{y}} {t}+\frac{\mathrm{1}}{\mathrm{2}}{at}^{\mathrm{2}} \\ $$$$\Rightarrow{h}=\left({u}\mathrm{sin}\theta\right){t}−\frac{\mathrm{1}}{\mathrm{2}}{gt}^{\mathrm{2}} \:\Rightarrow{gt}^{\mathrm{2}} −\mathrm{2}\left({u}\mathrm{sin}\theta\right){t}+\mathrm{2}{h}=\mathrm{0} \\ $$$$\Rightarrow{t}=\frac{\mathrm{2}{u}\mathrm{sin}\theta\pm\sqrt{\mathrm{4}{u}^{\mathrm{2}} \mathrm{sin}^{\mathrm{2}} \theta−\mathrm{8}{gh}}}{\mathrm{2}{g}} \\ $$$$\Rightarrow{t}=\frac{{u}\mathrm{sin}\theta+\sqrt{{u}^{\mathrm{2}} \mathrm{sin}^{\mathrm{2}} \theta−\mathrm{2}{gh}}}{{g}}\:…\left({ii}\right) \\ $$$$\left({i}\right)=\left({ii}\right) \\ $$$$\Rightarrow\frac{{R}}{{u}\mathrm{cos}\theta}=\frac{{u}\mathrm{sin}\theta+\sqrt{{u}^{\mathrm{2}} \mathrm{sin}^{\mathrm{2}} \theta−\mathrm{2}{gh}}}{{g}} \\ $$$$\Rightarrow{R}=\frac{\left({u}\mathrm{sin}\theta\right)\left({u}\mathrm{cos}\theta\right)+{u}\mathrm{cos}\theta\sqrt{{u}^{\mathrm{2}} \mathrm{sin}^{\mathrm{2}} \theta−\mathrm{2}{gh}}}{{g}} \\ $$
Commented by Best1 last updated on 18/Oct/22
$${is}\:{this}\:{the}\:{same}\:{as}\:\frac{\left({ucos}\theta\right)\left({usin}\theta\right)+\sqrt{{sin}\theta^{\mathrm{2}} −\mathrm{2}{gh}}}{{g}}??? \\ $$
Commented by Ar Brandon last updated on 18/Oct/22
$$\mathrm{I}\:\mathrm{think}\:\mathrm{this}\:\mathrm{isn}'\mathrm{t}\:\mathrm{correct}\:\mathrm{as}\:\mathrm{the}\:\mathrm{dimensions}\: \\ $$$$\mathrm{aren}'\mathrm{t}\:\mathrm{the}\:\mathrm{same}. \\ $$