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
Answer: Physical changes only change the appearance of a substance, not its chemical composition. Chemical changes cause a substance to change into an entirely substance with a new chemical formula. Chemical changes are also known as chemical reactions.
Explanation:
The one that will change the velocity of a periodic wave is :
B. Changing the medium of the wave
Waves is always determined by the properties of the medium, which means that changing the medium will change the velocity of the wave
hope this helps
If the force and the motion are along the same direction (like it is here) then work is force*distance. The time doesn't come into play until you want the power used. So here
W=9.0*3.0=27J
