Help relativity exam in in 5 hours

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To solve the kinetic energy of an electron with mass 9.11e-31 kg and momentum 4e-22, the formula E² = m₀²c⁴ + p²c² is essential. This equation allows the calculation of total energy, from which rest energy can be subtracted to find kinetic energy. The correct kinetic energy is 6.3e-14 J, but the challenge arises from the lack of velocity information. Understanding the relationship between momentum and energy in relativity is crucial for solving such problems. Memorizing this formula is recommended for anyone studying Special Relativity.
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urgent help relativity exam in in 5 hours

an electrion with mass 9.11e031 kg has momentum 4e-22. what is its kinetic energy

the answer is 6.3e-14 J but i have no idea how to get here

relativity kinetic energy = (y-1)mc^2 where y = 1/(square root of 1-(v^2/c^2)

momentum = ymu

thats as far as i can get , how the hell can u solve this type of problem if they don't give u the velocity of the electron?
 
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i got 8.78e-14

when plugging into that equation?
 
Use this
E^{2}=m_{0}^{2}c^{4}+p^{2}c^{2} to find the total energy and then from that simply subtract the rest energy...

Daniel.
 
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thank u! i was stuck on that problem forever
 
U'd better memorize that formula.It's the most important in the Special Relativity,at least,not in Minkowski space.

Daniel.
 
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