Separate the barriers so they have a 2cm gap between them.
Answer: potential energy but no kinetic energy
Explanation:
Since the rock is stationary, velocity is zero, therefore no kinetic energy,but there's potential energy because the rock is at rest,
According to the Jefferson lab, "The scientific definition of work is: using a force to move an object a distance (when both the force and the motion of the object are in the same direction.)"
Answer:
Increase 9 times
Explanation:
We have Newton formula for attraction force between 2 objects with mass and a distance between them:

where
is the gravitational constant.
is the masses of the 2 objects. and R is the distance between them.
Since the force is inversely proportional to the distance squared, if it is reduced by 3 times, the gravitational force between them would increase by
times