I am pretty sure the answer is C.
You have traveled 390 km. In order to find your answer all you have to do is multiply your speed which is 130 km/h by 3 hrs. That's my friend is how you get your answer! Have a great day!
The new speed of car is 10.9 m/s
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According to the principle of momentum conservation, momentum is only modified by the action of forces as they are outlined by Newton's equations of motion; momentum is never created nor destroyed inside a problem domain.
Mass of the railroad car, m₁ = 7950 kg
Mass of the load, m₂ = 2950 kg
It can be assumed as the speed of the car, u₁ = 15 m/s
Initially, it is at rest, u₂ = 0
Let v is the speed of the car. It can be calculated using the conservation of momentum as :




Therefore, the new speed of care is 10.9 m/s
Learn more about momentum here:
brainly.com/question/22257327
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That ratio is called"efficiency". It doesn't need to be a percent.
It can just as well be a fraction or a decimal number.