Answer:
A) T.
Explanation:
Kepler's third law states that the orbital period (T) of a satellite is related with the radius (R) and the mass of the object (M) it orbits:
So the orbital period is independent of the mass of the satellite, that means no matter the mass every satellite at a radius R around the earth have an orbital period A.
........................z......
To solve this problem we will use the concepts related to gravitational acceleration and centripetal acceleration. The equality between these two forces that maintains the balance will allow to determine how the rigid body is consistent with a spherically symmetric mass distribution of constant density. Let's start with the gravitational acceleration of the Star, which is

Here



Mass inside the orbit in terms of Volume and Density is

Where,
V = Volume
Density
Now considering the volume of the star as a Sphere we have

Replacing at the previous equation we have,

Now replacing the mass at the gravitational acceleration formula we have that


For a rotating star, the centripetal acceleration is caused by this gravitational acceleration. So centripetal acceleration of the star is

At the same time the general expression for the centripetal acceleration is

Where
is the orbital velocity
Using this expression in the left hand side of the equation we have that



Considering the constant values we have that


As the orbital velocity is proportional to the orbital radius, it shows the rigid body rotation of stars near the galactic center.
So the rigid-body rotation near the galactic center is consistent with a spherically symmetric mass distribution of constant density
Answer: The work is 1863 N*m
Explanation:
We can define work as:
W = F*d
Where F is the force that the mover needs to apply to the refrigerator, and d is the distance that the refrigerator is moved.
To move the refrigerator, the minimal force that the mover needs to do is exactly the friction force (In this case, the refrigerator will move with constant speed).
Then we will have:
F = 230 N
and the distance is 8.1 meters, then the work will be:
W = 230N*8.1 m = 1863 N*m
Answer:
I am pretty sure it is B.
Explanation:
I hope this helped if it didn't I am truly sorry