Uhhhh...you should have paid attention in class, just saying...
A particle that is smaller than an atom or a cluster of particles.
Answer:
Moment of inertia of the system is 289.088 kg.m^2
Explanation:
Given:
Mass of the platform which is a uniform disk = 129 kg
Radius of the disk rotating about vertical axis = 1.61 m
Mass of the person standing on platform = 65.7 kg
Distance from the center of platform = 1.07 m
Mass of the dog on the platform = 27.3 kg
Distance from center of platform = 1.31 m
We have to calculate the moment of inertia.
Formula:
MOI of disk = 
Moment of inertia of the person and the dog will be mr^2.
Where m and r are different for both the bodies.
So,
Moment of inertia
of the system with respect to the axis yy.
⇒ 
⇒ 
⇒ 
⇒
The moment of inertia of the system is 289.088 kg.m^2
The width is 2.5 cm long and could not be the right answer
Answer:

Explanation:
As we know that system of two boxes are moving on frictionless surface
So here if two boxes are considered as a system
then we have






Now since we know that both the boxes are moving together so force applied by first box on other box is given as


