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Angular momentum Question

  • #1

Homework Statement


Harry Potter is sitting 2.0 meters from the center of a merry-go-round when Draco Malfoy casts a spell that glues
Harry in place and then makes the merry-go-round start spinning on its axis. Harry has a mass of 50.0 kg and can
withstand 5:0 g's of acceleration before passing out. What is the magnitude of Harry's angular momentum when
he passes out?


Homework Equations


T=I alpha
L=mvr


The Attempt at a Solution



Assuming that the spell is a force then rF = I alpha. And using alpha = a/r, we using the max acceleration of 5g that
5mgr = Ia/r
However I'm not sure where to go from this, how do i get v? as time is unknwon
 

Answers and Replies

  • #2
1,137
0

Homework Statement


Harry Potter is sitting 2.0 meters from the center of a merry-go-round when Draco Malfoy casts a spell that glues
Harry in place and then makes the merry-go-round start spinning on its axis. Harry has a mass of 50.0 kg and can
withstand 5:0 g's of acceleration before passing out. What is the magnitude of Harry's angular momentum when
he passes out?
Lets look at the second eqn you mentioned,
L=mvr
you have m,r. what you need is v

Now, what do you think the acceleration 5g is acting along (direction)?
 
  • #3
oh i see mv^2/r = ma a=5g :D
thanks!
 

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