Answer:
(D) the sphere
Explanation:
The bodies given are Disk and Solid sphere (uniform sphere)
Moment of inertia of the bodies are
I(disk) =
I(sphere) = 
Since the moment of inertia of sphere is less than that of disk, therefore sphere will reach the bottom first.
C. Both A. and B.
Explanation:
Statement A. Reducing the volume is true because of Boyle's law, which states that for a gas at fixed temperature, the pressure p and the volume V are inversely proportional:

Therefore, when the volume V is reduced, the pressure p increases.
Statement B. Adding more gas is also true: in fact, if we add gas into the container, we will have more molecules of the gas hitting the wall of the container. But the pressure of a gas is exactly given by this: by the collision of the molecules against the wall of the container, so the more the molecules of gas, the greater the pressure.
Separate the barriers so they have a 2cm gap between them.
Answer:
The best option is for the following option m = 15 [g] and V = 5 [cm³]
Explanation:
We have that the density of a body is defined as the ratio of mass to volume.

where:
Ro = density = 3 [g/cm³]
Now we must determine the densities with each of the given values.
<u>For m = 7 [g] and V = 2.3 [cm³]</u>
![Ro=7/2.3\\Ro=3.04 [g/cm^{3} ]](https://tex.z-dn.net/?f=Ro%3D7%2F2.3%5C%5CRo%3D3.04%20%5Bg%2Fcm%5E%7B3%7D%20%5D)
<u>For m = 10 [g] and V = 7 [cm³]</u>
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<u>For m = 15 [g] and V = 5 [cm³]</u>
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<u>For m = 21 [g] and V = 8 [cm³]</u>
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