JEE Mains · Physics · STD 11 - 5. work,energy,power and collision
Three masses \(m,\,2\,m\) and \(3\,m\) are moving in \(x-y\) plane with speed \(3\,u,\,2\,u\,\) and \(u\) respectively as shown in figure. The three masses collide at the same point at \(P\) and stick together. The velocity of resulting mass will be

- A \(\frac{u}{{12}}\left( {\hat i\, + \,\sqrt 3 \hat j} \right)\)
- B \(\frac{u}{{12}}\left( {\hat i\, - \,\sqrt 3 \hat j} \right)\)
- C \(\frac{u}{{12}}\left( {-\hat i\, + \,\sqrt 3 \hat j} \right)\)
- D \(\frac{u}{{12}}\left( {-\hat i\, - \,\sqrt 3 \hat j} \right)\)
Answer & Solution
Correct Answer
(D) \(\frac{u}{{12}}\left( {-\hat i\, - \,\sqrt 3 \hat j} \right)\)
Step-by-step Solution
Detailed explanation
From the law of consevation of momentum we know that, \(\begin{array}{l} {m_1}{u_1} + {m_2}{u_2} + ...... = {m_1}{v_1} + {m_2}{v_2} + ....\\ Given\,{m_1}\, = \,m,{m_2} = 2m\,and\,{m_3} = 3m\\ and\,{u_1} = 3u,\,{u_2} = 2u\,and\,{u_3} = u \end{array}\) Let the velocity when the…
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