Alpha particle momentum

In summary: I used numbers in the back of our book that our homework is based off of. In summary, the alpha particle has a small initial momentum and collides with the gold nucleus. The collision produces a large amount of energy, which is eventually released as heat.
  • #1
flyboy9
10
0

Homework Statement


An alpha particle (a helium nucleus, containing 2 protons and 2 neutrons) starts out with kinetic energy of 10 MeV (10*10^6 eV), and heads in the +x direction straight toward a gold nucleus (containing 79 protons and 118 neutrons). The particles are initially far apart, and the gold nucleus is initially at rest. Answer the following questions about the collision.
What is the initial momentum of the alpha particle? (You may assume its speed is small compared to the speed of light).


Homework Equations


1 ev=1.69e-19 J= 1.69e-19 kg*m2/s2
K=.5*m*v2
p=m*v
mproton=mneutron=1.7e-27 kg

The Attempt at a Solution


I solved for velocity of the particle then multiplied it by its mass to find momentum.
10*1.69e-19=.5*m*v2
3.38e-18=8.8e-27*v2
497058823.5=v2
22294.81607=v

P=mv
P=8.8e-27*22294.81607
P=1.96194e-22
 
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  • #2
um, yeh. It seems correct.
 
  • #3
i thought so too... maybe the online program has the wrong answer.
 
  • #4
10 Mega-eV ...
 
  • #5
lightgrav said:
10 Mega-eV ...

what about it?
 
  • #6
the solution you posted started with 10 eV , not 10 MeV ... Mega = 1 000 000 .
 
  • #7
lightgrav said:
the solution you posted started with 10 eV , not 10 MeV ... Mega = 1 000 000 .

I would have never caught that. Thank you. The process seems correct to you?
 
  • #8
the PROCESS looks okay, but where did you get m = 8.8e-27 kg ?

by the way, p^2 /2m is USUALLY more useful than ½mv^2 ... especially in collisions !
 
  • #9
lightgrav said:
the PROCESS looks okay, but where did you get m = 8.8e-27 kg ?

by the way, p^2 /2m is USUALLY more useful than ½mv^2 ... especially in collisions !

I used numbers in the back of our book that our homework is based off of
 
  • #10
proton mass is 1.673 e-27kg ... only keeping 2 digits leads to severe roundoff error.

But I was asking "what computation did you use" which yielded that as the answer.
... it is a "leading" question
 
  • #11
lightgrav said:
proton mass is 1.673 e-27kg ... only keeping 2 digits leads to severe roundoff error.

But I was asking "what computation did you use" which yielded that as the answer.
... it is a "leading" question
This homework which is based off of our book only uses 2 significant digits for mass of proton and neutron.
total mass = 4*1.7e-27
= 6.8e-27

I apologize for the typo earlier as well.
 
Last edited:

What is an alpha particle?

An alpha particle is a type of subatomic particle that consists of two protons and two neutrons. It is identical to the nucleus of a helium atom.

What is momentum?

Momentum is a measure of an object's motion, and is defined as the product of its mass and velocity.

How is alpha particle momentum calculated?

The momentum of an alpha particle can be calculated using the equation p = mv, where p is momentum, m is mass, and v is velocity.

Why is alpha particle momentum important in nuclear reactions?

Alpha particle momentum is important in nuclear reactions because it determines how particles will behave and interact with each other, and can help predict the outcome of a reaction.

How does alpha particle momentum affect the stability of an atom?

The momentum of an alpha particle can affect the stability of an atom by determining the amount of energy released during a nuclear reaction. If the momentum is too high, the atom may become unstable and undergo radioactive decay.

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