VIT Engineering VIT Engineering Solved Paper-2009

  • question_answer
    A body is projected vertically upwards from the surface of the earth with a velocity equal to half the escape velocity. If R is the radius of the earth, maximum height attained by the body from the surface of the earth is

    A)  \[\frac{R}{6}\]                

    B)  \[\frac{R}{3}\]

    C)  \[\frac{2R}{3}\]               

    D)  \[R\]  

    Correct Answer: B

    Solution :

    Maximum height attained by a projectile \[h=\frac{{{v}^{2}}R}{2gR-{{v}^{2}}}\]                 ?.(i) Velocity of body = half the escape velocity \[v=\frac{{{v}_{e}}}{2}\] or \[v=\frac{\sqrt{2gR}}{2}\] \[\Rightarrow \] \[{{v}^{2}}\frac{2gR}{4}\] or \[{{v}^{2}}=\left( \frac{gR}{2} \right)\] Now, putting value of \[{{v}^{2}}\] in Eq. (i), we get \[h=\frac{\frac{gR}{2}.R}{2gR-\frac{gR}{2}}\] \[=\frac{g{{R}^{2}}/2}{3gR/2}\] or \[h=\frac{R}{3}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner