Question

Help me with this problem please

Answer 1

Total moment of inertia when arms are extended: 1.613
`kg\,m^2`

Step-by-step explanation:

This second part of the problem could be a pretty complex one, but if they expect you to do a simple calculation, which is what I imagine, the idea is just adding another moment of inertia to the first one due to the arms extended laterally and use the moment of inertia for such as depicted in the image I am attaching.

In that image:

L is the length from one end to the other of the extended arms (each 0.75m from the center of the body) which gives 1.5 meters.

m is the mass of both arms. That is: twice 5% of the mass of the person: which mathematically can be written as: 2 * 0.05 * 56.5 = 5.65 kg

Therefore this moment of inertia to be added can be obtained using the formula shown in the image:

`I_z=(1)/(12) \,m\,L^2\\\\I_z=(5.65\,*\,1.5^2)/(12) \\I_z=1.05937\,kg\,m^2`

Now, one needs to add this to the previous moment that you calculated, resulting in:

0.554 + 1.059 = 1.613
`kg\,m^2`