Question

a train car has a mass of 10,000 kg and is moving at +3.0 m/s. it strikes an identical train car that is at rest. the train cars combine. what is the magnitude of the final velocity of the combined cars? 0 m/s 1.5 m/s 3.0 m/s 6.0 m/s

Explanation:

Step1: Apply conservation of momentum

$m_1v_1=(m_1 + m_2)v_f$
Since $m_1=m_2 = 10000$ kg and $v_1 = 3.0$ m/s.

Step2: Solve for $v_f$

$v_f=\frac{m_1v_1}{m_1 + m_2}=\frac{10000\times3.0}{10000 + 10000}=1.5$ m/s

Answer:

1.5 m/s