JEE Main & Advanced Physics Motion in a Straight Line / सरल रेखा में गति Question Bank Motion Under Gravity

  • question_answer
    A body is slipping from an inclined plane of height \[h\] and length \[l\]. If the angle of inclination is \[\theta \], the time taken by the body to come from the top to the bottom of this inclined plane is 

    A)             \[\sqrt{\frac{2h}{g}}\]           

    B)             \[\sqrt{\frac{2l}{g}}\]

    C)             \[\frac{1}{\sin \theta }\sqrt{\frac{2h}{g}}\]  

    D)             \[\sin \theta \sqrt{\frac{2h}{g}}\]

    Correct Answer: C

    Solution :

                    Force down the plane\[=mg\sin \theta \]             \[\therefore \] Acceleration down the plane \[=g\sin \theta \]             Since \[l=0+\frac{1}{2}g\sin \theta {{t}^{2}}\]             \[\therefore \]\[{{t}^{2}}=\frac{2l}{g\sin \theta }=\frac{2h}{g{{\sin }^{2}}\theta }\Rightarrow t=\frac{1}{\sin \theta }\sqrt{\frac{2h}{g}}\]


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