According to the universal law of gravitation, if the separation between two planets is increased by a factor of 8, how many times weaker will their mutual pull of gravity be?

weakens by 64 times  

Explanation:

According to universal law of gravitation the force between two bodies is inversely proportional to square of their distance between them that F is inversely proportional to

So if we increase the the distance between two planets by 8 times then the the mutual attraction between will be decrease by times  

answer would be letter choice (a),   a ball resting on a shelf. would be another example of potential energy   >   stored energy > not moving.

a ball spinning on a finger   >   kinetic energy > moving energy

a ball rolling on the ground   >   kinetic energy   > moving energy

a   ball flying through the air   > kinetic energy   >   moving energy

hope that                                         : )

this is poiselle's equation from fluid mechanic in physics. mech eng