A rope is used to lower vertically a block of mass M by a distance x with a constant downward accele

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5.Work, Energy, Power and Collision

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A rope is used to lower vertically a block of mass $M$ by a distance $x$ with a constant downward acceleration $\frac{g}{2}$. The work done by the rope on the block is

A

$Mgx$

B

$\frac{1}{2}\,Mg{x^2}$

C

$-\frac{1}{2}\,Mg{x}$

D

$Mgx^2$

Solution

$\mathrm{W}=\overrightarrow{\mathrm{F}} \cdot \overrightarrow{\mathrm{d}}$

$\mathrm{Mg}-\mathrm{T}=\mathrm{Mg} / 2$

$\mathrm{W}=-\frac{1}{2} \mathrm{Mgx}$

Standard 11

Physics

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