The velocity of the board relative to the ice is zero, since both are at rest.
<h3>What is relative velocity?</h3>
Relative velocity is the velocity of an object in relation to another reference object or point.
When two objects are travelling or moving with the same velocity in the same direction, the relative velocity one relative to the other is zero.
Also, when two objects are at rest, the relative velocity one relative to the other is zero.
Therefore, the velocity of the board relative to the ice is zero, since both are at rest.
Learn more about relative velocity at: brainly.com/question/24337516
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Gravitational force depends on inverse square law. That is, gravitational force is inversely proportional to square of distance between asteroids.
As distance between them decreases, gravitational force increases. Hence A is correct.
Yes. sound waves are produced by energy.