* Source: Alpha particles are emitted from radioactive decay. Different radioactive isotopes emit alpha particles with different energies, which directly translates to different speeds.
* Medium: The speed of an alpha particle slows down as it travels through a medium due to collisions with atoms. This is why they have a limited range (typically only a few centimeters in air).
Typical speeds:
* At emission: Alpha particles from common radioactive sources like Polonium-210 or Americium-241 have speeds around 10% to 20% the speed of light.
* After travelling a distance: As the particle slows down, its speed drops significantly, especially in denser mediums.
Calculating speed:
The kinetic energy of an alpha particle can be used to calculate its speed:
* Kinetic energy (KE) = 1/2 * mass * velocity²
* Mass of an alpha particle ≈ 6.644657 × 10^-27 kg
To summarize:
Alpha particles travel at various speeds depending on the source and medium. At emission, they can be very fast, but they slow down significantly as they travel.
