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3-2.Motion in Plane
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A missile is fired for maximum range at your town from a place $100\, km$ away from you. If the missile is first detected at its half way point, how much warning time will you have ? (Take $g = 10\, m/s^2$) what was the speed of missile when it was detected ?
A$100\, m/s$
B$500\, m/s$
C$500\sqrt 2 \, m/s$
D$100\sqrt 2 \, m/s$
Solution
$u \cos \theta=\sqrt{g R} \times \frac{1}{\sqrt{2}}$
$=\sqrt{10 \times 10^{5}} \times \frac{1}{\sqrt{2}}=\frac{1000}{\sqrt{2}}$
$=\frac{500 \times 2}{\sqrt{2}}=500 \sqrt{2} \mathrm{m} / \mathrm{s}$
$=\sqrt{10 \times 10^{5}} \times \frac{1}{\sqrt{2}}=\frac{1000}{\sqrt{2}}$
$=\frac{500 \times 2}{\sqrt{2}}=500 \sqrt{2} \mathrm{m} / \mathrm{s}$
Standard 11
Physics
