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 particle moves along a straight line OX. At a time t (in second) the distance x (in metre) of the particle from O is given by \[x=40+12t-{{t}^{3}}\]. How long would the particle travel before coming to rest?

    A) 24 m    

    B) 40 m

    C) 56 m

    D) 16 m

    Correct Answer: C

    Solution :

    When particle comes to rest, \[\text{V=0=}\frac{\text{dx}}{\text{dt}}\text{=}\frac{\text{d}}{\text{dt}}\left( 40+12\text{t}-{{\text{t}}^{3}} \right)\] \[\Rightarrow 12-3{{\text{t}}^{\text{2}}}=0\] \[\Rightarrow {{\text{t}}^{\text{2}}}=\frac{12}{3}=4\text{   }\therefore \text{t=2 sec}\] Therefore distance travelled by particle before coming to rest, \[x=40+12t-{{t}^{3}}=40+12\times 2-{{\left( 2 \right)}^{3}}=56\text{m}\]


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