Question #2f246

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Question #2f246

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Answer 1 · 2017-02-22T16:36:49

$36 %$ $36%$

Explanation:

Let the velocity be $= v$ $=v$
Kinetic energy $= \frac{1}{2} m v^{2} = 0.5 m v^{2}$ $=1/2mv^2=0.5mv^2$

The velocity is decreased by $20 %$ $20%$
$\Rightarrow$ $=>$ New velocity $= v - v \times 20 % = 0.8 v$ $=v-vxx20%=0.8v$
New Kinetic energy $= \frac{1}{2} m {(0.8 v)}^{2} = 0.32 m v^{2}$ $=1/2m(0.8v)^2=0.32mv^2$

Decrease in kinetic energy $= 0.5 m v^{2} - 0.32 m v^{2} = 0.18 m v^{2}$ $=0.5mv^2-0.32mv^2=0.18mv^2$
$%$ $%$ Decrease in kinetic energy $= \frac{0.18 m v^{2}}{0.5 m v^{2}} \times 100 = 36$ $=(0.18mv^2)/(0.5mv^2)xx100=36$

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Question #2f246

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