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Physics Particle Decay Question (Cons. of Momentum?)

  • #1
Physics Particle Decay Question (Cons. of Momentum??)

Homework Statement


An isotope of Polonium 210Po with mass 3.49x10^-25 kg can decay into an alpha-particle(He Nucleus) with mass of 6.64x10^-27 kg and an isotope of lead 206Pb with a mass of 3.42x10^-25. If the polonium decays at rest. and the final decay products have a total KE of 8.65x10^-13 J, what are the speeds of the He and Pb nuclei?

Homework Equations



(m1+m2)Vo = m1v1 + m2v2


The Attempt at a Solution



My first thought was to plug in what was given but then I get stuck...

(Po)(0) = (He)(V_He) + (Pb)(V_Pb)

That gets me nowhere.

It's multiple choice

A. 0.17 m
B. 0.15 m
C. 0.08 m
D. 0.03 m
E. 0.00 m

I wish I could show more work, I just dont know where to go with it at all
 

Answers and Replies

  • #2
Simon Bridge
Science Advisor
Homework Helper
17,848
1,645
All conservation of momentum problems have the same pattern.

step 1. sketch the situation "before" ... in this case you have a Po nucleus.
... draw on the momentum arrow and label it ... in this case, what is the initial momentum?

step 2. sketch the situation "after" ... in this case you have two particles.
... which directions to they head off in (compared to each other)?
... draw the momentum arrows and label them. Leave variable names for anything you don't know.

Is there a relationship between kinetic energy and momentum you can exploit?

Step 3. total momentum before = total momentum after.
 

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