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A ball kept at $20 \mathrm{~m}$ height falls freely in downward direction vertically and hits the ground. The coefficient of restitution is $0.4 .$ After the first rebound the upward
velocity is $\left[\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^{2}\right]$
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velocity is $\left[\mathrm{g}=10 \mathrm{~m} / \mathrm{s}^{2}\right]$
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Verified Answer
The correct answer is:
$8 \mathrm{~m} / \mathrm{s}$
$8 \mathrm{~m} / \mathrm{s}$
$h=20 \mathrm{~m}, \mathrm{e}=0.4 \mathrm{~m}$
$\therefore v^{2}=0+2 g h=2 \times 10 \times 20$
$\therefore v=2 \times 10=20$
$e=\frac{\mathrm{u}}{\mathrm{v}}$
$\therefore \mathrm{u}=\mathrm{ev}=0.4 \times 20=8 \mathrm{~m} / \mathrm{s}$
$h=20 \mathrm{~m}, \mathrm{e}=0.4 \mathrm{~m}$
$\therefore v^{2}=0+2 g h=2 \times 10 \times 20$
$\therefore v=2 \times 10=20$
$e=\frac{\mathrm{u}}{\mathrm{v}}$
$\therefore \mathrm{u}=\mathrm{ev}=0.4 \times 20=8 \mathrm{~m} / \mathrm{s}$
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