JEE Main & Advanced Physics Motion in a Straight Line / सरल रेखा में गति Question Bank Self Evaluation Test - Motion in a Strainght Line

  • question_answer
    A rocket is fired upward from the earth's surface such that it creates an acceleration of \[19.6\,\,m{{s}^{-2}}\]. If after 5 s, its engine is switched off, the maximum height of the rocket from earth's surface would be

    A) 980 m  

    B) 735 m  

    C) 490 m  

    D) 245 m

    Correct Answer: B

    Solution :

    Velocity when the engine is switched off \[v=19.6\times 5=98\text{ m}{{\text{s}}^{-1}}\text{      }{{\text{h}}_{\max }}={{h}_{1}}+{{h}_{{}}}\] Where  \[{{\text{h}}_{\text{1}}}\text{=}\frac{\text{1}}{\text{2}}\text{a}{{\text{t}}^{\text{2}}}\text{,   }{{\text{h}}_{\text{2}}}\text{=}\frac{{{\text{v}}^{\text{2}}}}{\text{2a}}\] \[{{h}_{\max }}=\frac{1}{2}\times 19.6\times 5\times 5+\frac{98\times 98}{2\times 9.8}=73.5\text{ m}\]


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