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  • Help me answer: A block of mass m is kept on a platform which starts from rest with constant acceleration g/2 upward, as shown in the figure. Work done by normal reaction on block in time t is:

A block of mass m is kept on a platform which starts from rest with constant acceleration g/2 upward, as shown in the figure. Work done by normal reaction on block in time t is:

  • Option 1)

    - \frac{mg^{2}t^{2}}{8}

  • Option 2)

    \frac{mg^{2}t^{2}}{8}

  • Option 3)

     

    0

  • Option 4)

     

    \frac{3mg^{2}t^{2}}{8}

Answers (1)

best_answer

 

Definition of work by constant force -

w = \underset{F}{\rightarrow}.\underset{S}{\rightarrow}

- wherein

The scalar product of the force vector (\underset{F}{\rightarrow}) and the displacement vector (\underset{S}{\rightarrow})

 

W_{N}=\vec{N}.\vec{S}\\\\\\N-Mg=\frac{Mg}{2}\Rightarrow N=\frac{3mg}{2}\\\\\\and \: \: \vec{S}=\frac{1}{2}\vec{g}t^{2}\\\\W=\frac{3mg^{2}t^2}{4}


Option 1)

- \frac{mg^{2}t^{2}}{8}

Option 2)

\frac{mg^{2}t^{2}}{8}

Option 3)

 

0

Option 4)

 

\frac{3mg^{2}t^{2}}{8}
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