Answer:
The correct option is b) In galaxy clusters
Explanation:
A type of galaxy that appear elliptical in shape and have an almost featureless and smooth image is known as the elliptical galaxy.
An elliptical galaxy is three dimensional and consists of more than one hundred trillion stars which are present in random orbits around the centre.
Elliptical galaxy is generally found in the galaxy clusters.
To solve this problem it is necessary to apply the kinematic equations of angular motion.
Torque from the rotational movement is defined as

where
I = Moment of inertia
For a disk
Angular acceleration
The angular acceleration at the same time can be defined as function of angular velocity and angular displacement (Without considering time) through the expression:

Where
Final and Initial Angular velocity
Angular acceleration
Angular displacement
Our values are given as






Using the expression of angular acceleration we can find the to then find the torque, that is,




With the expression of the acceleration found it is now necessary to replace it on the torque equation and the respective moment of inertia for the disk, so




Therefore the torque exerted on it is 
Hello!
Answer:
2000 J
Explanation
Work equation is expressed as:

Where:
F: Applied force
d: traveled distance
α: Angle between the direction of the force and the direction of the movement. (in this case, both of the direction are the same, so the angle is 0°)
By substituting:

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