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An observer having a gun observes a remotely controlled balloon. When he first noticed the balloon, it was at an altitude of `800m` and moving vertically upward at a constant velocity of `5m//s`. The horizontal displacement of balloon from the observer is `1600m`. Shells fired from the gun have an initial velocity of `400 m//s` at a fixed angle `theta ( sin theta =3//5 `and `cos theta =4//5 )`. The observer having gun waits `(` for some time after observing the balloon `)` and fires so as to destroy the balloon. Assume `g=10m//s^(2)`. Neglect air resistance. The flight time of the shell before it strikes the balloon isA. `2 sec `B. `5 sec`.C. `10 sec`D. `15 sec` |
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Answer» Correct Answer - B `(`Easy `)` The motion in the `x-` direction is a constant velocity motion. We find the flight time `=(1600m)/(u_(x))` `(1600)/(400costheta)=5 sec.` Flight time `=5 sec.` |
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