Rotational Inertia, Torque and Angular Acceleration (1Q)

[Sam Cepeda]

Homework Statement

. What is the angular acceleration if a force of 3 N is applied perpendicular to the radius of a 5 kg solid sphere that has a radius of 0.6 meters?

Homework Equations

= r x F
I = mr^2

The Attempt at a Solution

I used

tried solving for angular acce.
3N/(5kg)(0.6) =10rad/sec^2

Also, if the question had said "hollow sphere" would the moment of inertia be different..(2/3)mr^2 ?

 

[TSny]

Welcome to PF!

You do not have the correct expression for the moment of inertia of a solid sphere.
https://en.wikipedia.org/wiki/List_of_moments_of_inertia

Yes, for a hollow sphere, $I = (2/3)Mr^2$.

 

[SteamKing]

Homework Statement

. What is the angular acceleration if a force of 3 N is applied perpendicular to the radius of a 5 kg solid sphere that has a radius of 0.6 meters?

Homework Equations

= r x F
I = mr^2

The Attempt at a Solution

I used

tried solving for angular acce.
3N/(5kg)(0.6) =10rad/sec^2

Also, if the question had said "hollow sphere" would the moment of inertia be different..(2/3)mr^2 ?

For a solid sphere, I ≠ mR²; I = (2/5) M ⋅ R²

Here is a list of the mass moments of inertia for a variety of different shapes:

https://en.wikipedia.org/wiki/List_of_moments_of_inertia