A ball of mass m is thrown with a velocity v at a disk

[Westin]

Homework Statement

A ball of mass m is thrown with a velocity v at a disk of mass M which sticks to the rim on impact.https://s3.lite.msu.edu/res/msu/perl_author/P3_PRELECTURE/L_CONSERVATION/IMAGES/CQ1.png

For the system of the ball and disk, what is the total initial angular momentum about the axis?[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char68.png0,0,Rmv[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char69.png
[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char68.png0,0,−Rmv[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char69.png
[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char68.png0,−Rmv,0[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char69.png
[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char68.png0,Rmv,0[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char69.png
[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char68.png0,0,0[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char69.png[/B]

Homework Equations

Cross Product

The Attempt at a Solution

τ⃗ A=r⃗ A×F⃗
Cross Product
[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char68.png0,0,−Rmv[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char69.png

 

[robphy]

What is your specific question about this question?

 

[Westin]

Am I correct?

 

[robphy]

Yes, [PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char68.png0,0,−Rmv[PLAIN]https://s3.lite.msu.edu/adm/jsMath/fonts/cmsy10/alpha/144/char69.png, using the definition of angular momentum as L=r x p and the right-hand rule (presuming the axis is through the axis of the disk).

 

[paisiello2]

Right hand rule?