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A particle of mass 100 g is thrown vertically upwards with a speed of $5 \mathrm{~m} / \mathrm{s}$. The work done by the force of gravity during the time the particle goes up is
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-1.25 J
The height ( $h$ )traversed by particle while going up is
$h=\frac{u^2}{2 g}=\frac{25}{2 \times 9.8}$
Work done by gravity force $=m \overrightarrow{\mathbf{g}} \cdot \overrightarrow{\mathbf{h}}$
$=0.1 \times g \times \frac{25}{2 \times 9.8} \cos 180^{\circ}$
[Angle between force and displacement is $180^{\circ}$ ]
$\therefore W=-0.1 \times \frac{25}{2}=-1.25 \mathrm{~J}$
$h=\frac{u^2}{2 g}=\frac{25}{2 \times 9.8}$
Work done by gravity force $=m \overrightarrow{\mathbf{g}} \cdot \overrightarrow{\mathbf{h}}$
$=0.1 \times g \times \frac{25}{2 \times 9.8} \cos 180^{\circ}$
[Angle between force and displacement is $180^{\circ}$ ]
$\therefore W=-0.1 \times \frac{25}{2}=-1.25 \mathrm{~J}$
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