A 133 kg horizontal platform is a uniform disk of radius 1.95 m and can rotate about the vertical axis through its center. A 62.7 kg person stands on the platform at a distance of 1.19 m from the center, and a 28.5 kg dog sits on the platform near the person 1.45 m from the center. Find the moment of inertia of this system, consisting of the platform and its population, with respect to the axis.

The moment of inertia of the system is  

Explanation:

From the question we are told that

    The mass of the platform is  

     The  radius of the  platform is  r = 1.95 m

     The mass of the person is

     The position of the person from the center is  

       The mass of the dog is

     The position of the dog from the center is  

Generally the moment of inertia of the platform with respect to its axis is  mathematically represented as

The  moment of inertia of the person with respect to the axis is mathematically represented as

The  moment of inertia of the dog with respect to the axis is mathematically represented as

So the moment of inertia of the system about the axis  is mathematically evaluated as

=>      

substituting values  

a small object of mass 3.66 g and charge -17.6 µc is suspended motionless above the ground when immersed in a uniform electric field perpendicular to the ground. what are the magnitude and direction of the electric field?

r = ρ x length / area  

ρ = r x area / length  

ρ is in ohm-meters  

in basic units, it is m³kg/s³a²  

i think this is it.