Easy but confusing MCQ

JEE Mains Discussion Forum › Mechanics questions › Easy but confusing MCQ

If for a system of N particles of different masses m1, m2....mN with PVs r1, r2.....rN and corresponding velocities v1, v2...vN such that Î£vi = 0, then

1) The total momentum must be 0.
2) The total angular momentum must be independent of the choice of the origin.
3) The total force on the system must be 0.
4) The total torque on the system must be 0.

#Physics #Mechanics

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4 Answers

1

Anirudh Kumar ·2011-04-21 21:24:52

option 2 must be correct .

because

L = Î£m_iv_ir_i

now suppose the origin shifts to r_o

L_new = Î£m_iv_i(r_i-r_o)
= Î£m_iv_ir_i - 0

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Vivek @ Born this Way ·2011-04-22 02:17:04

Also 4?

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1

seoni ·2011-04-22 02:47:47

anirudh

how'd u put (Ro)sumation (Mi)(Vi)=0?
i dont think it shud be 0
only summation V i =0

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1

swordfish ·2011-04-23 01:01:14

Anirudh...that was my answer too but they gave 1st option as the correct one.

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