Opent top freight train with coal

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    Coal Train
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When a freight car moving at constant speed suddenly receives a large load of coal, its velocity will decrease due to the conservation of momentum. The initial momentum of the system is equal to the momentum after the coal is added, leading to a reduction in speed as the mass of the car increases. The equation m_1v_1 = m_2v_2 illustrates that since m2 (the mass after coal is added) is greater than m1 (the initial mass), the velocity must decrease. Therefore, the correct answer to the question is that the velocity of the car decreases. This discussion emphasizes the application of momentum conservation in analyzing changes in velocity due to mass alterations.
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Question 3 text A freight car moves along a frictionless level railroad track at constant speed. The car is open on top. A large load of coal is suddenly dumped into the car. What happens to the velocity of the car?
Question 3 answers
It increases.
It remains the same.
It decreases. <-----
cannot be determined from the information given
 
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Looks good to me. Use conservation of momentum to confirm.

m_1v_1 = m_2v_2

m2 is greater than m1 therefore v has to decrease.
 

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