9th Class Science Time and Motion Question Bank Motion

  • question_answer
    Two racing cars of masses \[{{m}_{1}}\] and \[{{m}_{2}}\] are moving in circles of radii \[{{r}_{1}}\] and \[{{r}_{2}}\] respectively. Their speeds are such that each makes a complete circle in the same length of time T. The ratio of angular speed of the first car to that of the second car is

    A) \[{{m}_{1}}:{{m}_{2}}\]                

    B) \[{{r}_{1}}:{{r}_{2}}\]       

    C)        \[1:1\]              

    D)        \[{{m}_{1}}{{r}_{1}}:{{m}_{2}}{{r}_{2}}\].                

    Correct Answer: C

    Solution :

    Both the cars make a complete circle in the same length of time T, which means that angular speeds of both cars are same. \[\because \omega =\frac{v}{r}=\frac{2\pi r}{Tr}=\frac{2\pi }{T}\]


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