The momentum of two or more objects during collisions is not lost nor gained
As the metal expands as does the road bed so neither really effevts those foing over the bridge. as it is hot the metal will expand and so will most tarmac on roads.
The answer is allotropes. Hope this helps. Have a great day.
Explanation:
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The blue car is moving with a velocity of -14 m/s using the red car as a reference frame.