A car covers \(A B\) distance with first one-third at velocity \(v _{1} ms ^{-1}\), second one-third at \(v _{2} ms ^{-1}\) and last one-third at \(v _{3} ms ^{-1}\). If \(v _{3}=3 v _{1}, v _{2}=2 v _{1}\) and \(v _{1}=11\,ms ^{-1}\) then the average velocity of the car is________ \(ms ^{-1} .\)

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Verified Solution

Answer & Solution

Correct Answer

(D) \(18\)

Detailed explanation

\(\langle\overrightarrow{ v }\rangle=\frac{\text { Displacement }}{\text { time }}\)

(Let displacement be \(l\) )

\(=\frac{\ell}{\left(\frac{\ell}{ V _{3}}+\frac{\ell}{ V _{2}}+\frac{\ell}{ V _{1}}\right) \frac{1}{3}}\)

\(=\frac{3}{\frac{1}{ V _{1}}+\frac{1}{ V _{2}}+\frac{1}{ V _{3}}}=\frac{3}{\frac{1}{11}+\frac{1}{22}+\frac{1}{33}}\)

\(=18\,m / s\)

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