Complete question
The complete question is shown on the first uploaded image
Answer:
The velocity is 
Explanation:
From the question we are told that
a = nb
The length of the minor axis of the symbol of the Federation, a circle, seen by the observer at velocity v must be equal to the minor axis(b) of the Empire's symbol, (an ellipse)
Now this length seen by the observer can be mathematically represented as

Here t is the actual length of the major axis of of the Empire's symbol, (an ellipse)
So t = a = nb
and b is the length of the minor axis of the symbol of the Federation, (a circle) when seen by an observer at velocity v which from the question must be the length of the minor axis of the of the Empire's symbol, (an ellipse)
i.e h = b
So
![[\frac{1}{n} ]^2 = 1 - \frac{v^2}{c^2}](https://tex.z-dn.net/?f=%5B%5Cfrac%7B1%7D%7Bn%7D%20%5D%5E2%20%3D%20%201%20-%20%20%5Cfrac%7Bv%5E2%7D%7Bc%5E2%7D)
![v^2 =c^2 [1- \frac{1}{n^2} ]](https://tex.z-dn.net/?f=v%5E2%20%3Dc%5E2%20%5B1-%20%5Cfrac%7B1%7D%7Bn%5E2%7D%20%5D)
![v^2 =c^2 [\frac{n^2 -1}{n^2} ]](https://tex.z-dn.net/?f=v%5E2%20%3Dc%5E2%20%5B%5Cfrac%7Bn%5E2%20-1%7D%7Bn%5E2%7D%20%5D)

I think the awnser is Dark Matter
Incomplete question as the unit of volume is not written correctly.So the complete question is here:
A straightforward method of finding the density of an object is to measure its mass and then measure its volume by submerging it in a graduated cylinder. What is the density of a 240-g rock that displaces 89.0 cm³?
Answer:

Explanation:
Given data
Mass m=240g
Volume V=89.0 cm³
To find
Density d
Solution
If rock displaces 89.0 cm³ of water means volume of rock is also 89cm³
So

Answer:
The net torque is zero
Explanation:
Let's assume that the dipole is compose of two equal but oposite charges e, and it cam be represented by a rod with one end having a charge e and the other end with a charge of -e. Notice that the dipole is parallel to the electric field thus the force felt by both of the charges will be parallel to the electric field. This means that there will be no components of the forces that are perpendicular to the rod which is a requirement for it to have a torque.
Answer:
Explanation:
Let T be the tension .
Applying newton's second law on the downward movement of the bucket
mg - T = ma
On the drum , a torque of TR will be acting which will create an angular acceleration of α in it . If I be the moment of inertia of the drum
TR = Iα
TR = Ia/ R
T = Ia/ R²
Replacing this value of T in the other equation
mg - T = ma
mg - Ia/ R² = ma
mg = Ia/ R² +ma
a ( I/ R² +m)= mg
a = mg / ( I/ R² +m)
mg - T = ma
mg - ma = T
mg - m x mg / ( I/ R² +m) = T
mg - m²g / ( I/ R² +m ) = T
mg - mg / ( 1 + I / m R² ) = T
b ) T = Ia/ R²
I = TR² / a
c ) Moment of inertia of hollow cylinder
I = 1/2 M ( R² - R² / 4 )
= 3/4 x 1/2 MR²
= 3/8 MR²
I / R² = 3/8 M
a = mg / ( I/ R² +m)
a = mg / ( 3/8 M + m )
T = Ia/ R²
= 3/8 MR² x mg / ( 3/8 M + m ) x 1 /R²
= 