The block M=4kg rests on a friction-less surface. The block is connected to the spring of a spring constant k=1250 N/m.

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The block M=4kg rests on a friction-less surface. The block is
connected to the spring of a spring constant k=1250 N/m. The other
end of the spring is fixed, and the spring initially is neither
stretched nor compressed. A second mass of m=2kg has a velocity of
20m/s. It strikes the first block with a completely inelastic
collision.
Determine the amplitude of the resultant periodic motion of M
(the larger mass).