Question

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

Answer 1

`v_(1i) = 6 m/s`

Step-by-step 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

`m_1v_(1i) + m_2v_(2i) = (m_1 + m_2) v_f`

here we have

`m_1 = 5000 kg`

`m_2 = 10,000 kg`

`v_(2i) = 0`

`v_f = 2 m/s`

now we have

`5000(v_(1i)) + 0 = (5000 + 10000) (2)`

`v_i = (15000)/(5000)(2)`

`v_(1i) = 6 m/s`