A block of mass m is kept on a platform which starts from rest wi… - Vidyadip

MCQ

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

A
$ - \frac{{m{g^2}{t^2}}}{8}$
B
$ \frac{{m{g^2}{t^2}}}{8}$
C
$0$
✓
$ \frac{{3m{g^2}{t^2}}}{8}$

✓

Answer

Correct option: D.

$ \frac{{3m{g^2}{t^2}}}{8}$

d
$\begin{array}{l}
W = F\cos \theta \\
\,\,\,\,\,\, = m\left( {g + \frac{g}{2}} \right) \times \left[ {\frac{1}{2} \times \frac{g}{2} \times {t^2}} \right]
\end{array}$

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