Answer:

Explanation:
- We have to make a hollow sphere of inner radius
and outer radius
.
Then the mass of the material required to make such a sphere would be calculated as:
Total volume of the spherical shell:

And the volume of the hollow space in the sphere:

Therefore the net volume of material required to make the sphere:


- Now let the density of the of the material be
.
<u>Then the mass of the material used is:</u>


Positive positive side naturally because protons always move to positive side and electron always move to negative side
The acceleration of the box is approximately 
Explanation:
According to Newton's second law of motion, the net force acting on the box is equal to the product between its mass and its acceleration:

where
is the net force
m = 12.0 kg is the mass of the box
a is the acceleration
The net force can be written as

where
is the applied forward force
is the friction force
Combining the two equations,

And solving for the acceleration,

Learn more about Newton's second law:
brainly.com/question/3820012
#LearnwithBrainly
Answer:
r = 6.4 cm
Explanation:
F = GMm/r²
r = √(GMm/F)
r = √((6.674e-11)(6.2e5)(13e3)/130)
r = 0.06432... m
Those are some high density materials!