AFMC AFMC Solved Paper-2007

  • question_answer
    The driver of a car travelling at velocity v suddenly sees a broad wall in front of him at a distance d. He should

    A) brake sharply                    

    B) turn sharply

    C) (a) and (b) both                               

    D) none of the above

    Correct Answer: A

    Solution :

    When driver applies brakes and the car covers distance \[x\] before coming to rest, under the effect of retarding force F then from work- energy theorem \[\frac{1}{2}m{{v}^{2}}=Fx\] \[\Rightarrow \]       \[x=\frac{m{{v}^{2}}}{F}\] But when he makes turn, then             \[\frac{m{{v}^{2}}}{r}=F\] \[\Rightarrow \]       \[r=\frac{m{{v}^{2}}}{F}\] It is clear that \[x=\frac{r}{2}\]i.e, by the same retarding force the car can be stopped in a less distance if the driver apply brakes. This retarding force is actually a friction force.


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