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Question-71054




Question Number 71054 by jagannath19 last updated on 11/Oct/19
Commented by jagannath19 last updated on 11/Oct/19
with explanation
$${with}\:{explanation} \\ $$
Commented by mr W last updated on 11/Oct/19
x=v cos θ t  y=v sin θ t−(1/2)gt^2   t=((v sin θ)/g)  y_(max) =((v^2  sin^2  θ)/(2g))=(v^2 /(4g))=100  ⇒(v^2 /g)=400  v cos θ t=300  t=((300)/(v cos θ))  y=t(v sin θ −(1/2)gt)=((300)/(v cos θ))(v sin θ−((300g)/(2 v cos θ)))  =300(tan θ−((300g)/(2 v^2  cos^2  θ)))  =300(1−((300)/(400)))  =75 m =height of ball
$${x}={v}\:\mathrm{cos}\:\theta\:{t} \\ $$$${y}={v}\:\mathrm{sin}\:\theta\:{t}−\frac{\mathrm{1}}{\mathrm{2}}{gt}^{\mathrm{2}} \\ $$$${t}=\frac{{v}\:\mathrm{sin}\:\theta}{{g}} \\ $$$${y}_{{max}} =\frac{{v}^{\mathrm{2}} \:\mathrm{sin}^{\mathrm{2}} \:\theta}{\mathrm{2}{g}}=\frac{{v}^{\mathrm{2}} }{\mathrm{4}{g}}=\mathrm{100} \\ $$$$\Rightarrow\frac{{v}^{\mathrm{2}} }{{g}}=\mathrm{400} \\ $$$${v}\:\mathrm{cos}\:\theta\:{t}=\mathrm{300} \\ $$$${t}=\frac{\mathrm{300}}{{v}\:\mathrm{cos}\:\theta} \\ $$$${y}={t}\left({v}\:\mathrm{sin}\:\theta\:−\frac{\mathrm{1}}{\mathrm{2}}{gt}\right)=\frac{\mathrm{300}}{{v}\:\mathrm{cos}\:\theta}\left({v}\:\mathrm{sin}\:\theta−\frac{\mathrm{300}{g}}{\mathrm{2}\:{v}\:\mathrm{cos}\:\theta}\right) \\ $$$$=\mathrm{300}\left(\mathrm{tan}\:\theta−\frac{\mathrm{300}{g}}{\mathrm{2}\:{v}^{\mathrm{2}} \:\mathrm{cos}^{\mathrm{2}} \:\theta}\right) \\ $$$$=\mathrm{300}\left(\mathrm{1}−\frac{\mathrm{300}}{\mathrm{400}}\right) \\ $$$$=\mathrm{75}\:{m}\:={height}\:{of}\:{ball} \\ $$

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