A body covers first one-third of distance with a velocity 20, ms^{-1} , second one-third with a velo

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2.Motion in Straight Line

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A body covers first one-third of the distance with a velocity $20\, ms^{-1}$, the second one-third with a velocity of $30\, ms^{-1}$ and last one-third with a velocity of $40\, ms^{-1}$. The average velocity is nearly........$m/s$

A

$28$

B

$38$

C

$18$

D

$8$

Solution

vel $=\frac{d}{\text { time }}$

$\frac{d}{\frac{d}{3 .20^{+}}+\frac{d}{3.30}+\frac{d}{3 \cdot 40}}=\frac{1}{\frac{1}{60}+\frac{1}{90}+\frac{1}{120}}$

$=\frac{360}{6+4+3}=\frac{360}{13}$

$=27.7 \mathrm{m} / \mathrm{s}$

$\approx 28 m/s$

Standard 11

Physics

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