Calculating Kinetic Energy of an Alpha Particle

In summary, the conversation is about a question regarding the calculation of energy using the equation E=mc^2. The individual asks for help and provides their attempt at a solution which is later corrected by the teacher. The summary concludes with the individual expressing their understanding and thanking the teacher.
  • #1
astri_lfc
7
0

Homework Statement

attachment.php?attachmentid=65090&stc=1&d=1387977546.jpg

could you help me for the question b?

Homework Equations


E = mc^2

The Attempt at a Solution



the mass of the alpha particle is 0.66466 x 10^-26 kg >> 4.022 u

put it into the equation, so
E = 4.022 x c x c = 3.615 x 10^17 eV >> 0.0579 joule

my answer is that, but my teacher answer is 1.89x10^-13 joule..

which one is true? can you show me where's my wrong?
 

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  • #2
Merry Xmas.

What you're calculating is the energy due to the (rest) mass of the alpha particle. That's not kinetic energy.

The alpha particle's total energy comprises energy due to its (rest) mass plus its kinetic energy. You need to determine the latter.

You can just work with mass, because mass and energy are basically equivalent (or proportional, depending on choice of units). Calculate the total mass of on the left hand side. Calculate the total mass on the right hand side. You may ignore the photon because at the minimum KE of the alpha particle, the photon will have no energy. Can you now figure out the "extra" mass on the LHS? Convert that to energy.
 
  • #3
merry christmas too ;)

thankyou :D i understand it now!
 

1. What is kinetic energy?

Kinetic energy is the energy an object possesses due to its motion.

2. What is an alpha particle?

An alpha particle is a type of particle that contains two protons and two neutrons, making it identical to a helium nucleus.

3. How is kinetic energy related to alpha particles?

Kinetic energy is related to alpha particles because alpha particles possess kinetic energy due to their motion.

4. How is kinetic energy calculated for an alpha particle?

Kinetic energy for an alpha particle can be calculated using the equation KE = 1/2 * mv^2, where m is the mass of the alpha particle and v is its velocity.

5. What is the unit of measurement for kinetic energy of an alpha particle?

The unit of measurement for kinetic energy of an alpha particle is joules (J).

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