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Three identical particles moving with velocities v0 i, -3v0 j and 5v0 k collide one after another and coalesce into a single particle. The velocity of the combined particle (in i, j, k form) is:

1. v0 (i - 3j + 5k)
2. v0/3 (i - 3j + 5k)
3. v0/2 (i - 3j + 5k)
4. v0/3 (i + 3j + 5k)

Correct answer: v0/3 (i - 3j + 5k)

Solution

Total momentum = m*v0(i - 3j + 5k), and the combined mass is 3m, so final velocity = v0/3 (i - 3j + 5k).

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