Answer:
7.5 kg
Explanation:
The mass of the train can be found by using the formula
[tex]m = \frac{2k}{ {v}^{2} } \\ [/tex]
k is the kinetic energy
v is the velocity
From the question we have
[tex]m = \frac{2(6000)}{ {40}^{2} } = \frac{12000}{1600} = \frac{120}{16} = \frac{15}{2} \\ [/tex]
We have the final answer as
7.5 kg
Hope this helps you
