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A 5000-kg freight car crashes into a 10,000-kg freight car at rest. They couple upon collision and move with a speed of 2 m/s. What was the initial speed of the 5000-kg freight car? A 5000-kg freight car crashes into a 10,000-kg freight car at rest. They couple upon collision and move with a speed of 2 m/s. What was the initial speed of the 5000-kg freight car? a) 4 m/s b) 8 m/s c) 6 m/s d) 5 m/s e) none of the above

Respuesta :

Answer:

[tex]v_{1i} = 6 m/s[/tex]

Explanation:

Here we know that the whole system is having no external force on it

So the total momentum of the system will remain conserved

So here we can say

[tex]m_1v_{1i} + m_2v_{2i} = (m_1 + m_2) v_f[/tex]

here we have

[tex]m_1 = 5000 kg[/tex]

[tex]m_2 = 10,000 kg[/tex]

[tex]v_{2i} = 0[/tex]

[tex]v_f = 2 m/s[/tex]

now we have

[tex]5000(v_{1i}) + 0 = (5000 + 10000) (2)[/tex]

[tex]v_i = \frac{15000}{5000}(2)[/tex]

[tex]v_{1i} = 6 m/s[/tex]