A 4.00 kg object is moving at 5.00 m/s WEST.It strikes a 6.00 kg that is moving WEST at 2.00 m/s.The objects have a one-dimensional elastic collision in the EAST-WEST direction.The velocity of the 6.00 kg object after the collision is
A) 1.40 m/s WEST.
B) 1.40 m/s EAST.
C) 4.40 m/s EAST.
D) 4.40 m/s WEST.
E) 3.00 m/s WEST.

Question

Quizplus · Accepted Answer

Using conservation of momentum, we have: 
(4.00 kg)(-5.00 m/s) + (6.00 kg)(-2.00 m/s) = (4.00 kg)v1 + (6.00 kg)v2
where v1 and v2 are the velocities of the 4.00 kg and 6.00 kg objects after the collision, respectively. 
Simplifying and solving for v2, we get: 
v2 = (-16.00 kg m/s + 20.00 kg m/s)/6.00 kg = 4.00/3 m/s EAST
Therefore, the answer is (C) 4.40 m/s EAST.

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