Answer:
The momentum would be doubled
Explanation:
The magnitude of the momentum of the freight train is given by:

where
m is the mass of the train
v is its speed
In this problem, we have that the speed of the train is unchanged, while the mass of the train is doubled:

therefore, the new momentum is

so, the momentum has also doubled.
No force is necessary to keep a moving object moving (in a straight line at a constant speed).
The change in the state of matter causes change in the motion of the particles of the matter. The gaseous state of matter has the greatest speed while the solid state has the least speed.
The change in state of every matter is accompanied by lost or gained of energy.
Example is water.
The solid state of water is ice. The motion of particles of the water is relatively zero because the molecules are held at a fixed position.
The liquid state of water occurs when the temperature of the ice is increased above zero degree Celsius. The speed of the particles of water in liquid state is greater than solid state.
The gaseous state of water occurs when the temperature of the liquid water is increased beyond 100 degree Celsius. The speed of water in gaseous state is greater than liquid state.
Learn more about different state of matter here: brainly.com/question/9402776
Ofcoure the elephante as the elephant has more weight