What is the momentum of an electron whose kinetic energy equals its rest mass,m?
A)0.5 mc kg.m/s
B) kg.m/s
C) kg.m/s
D) kg.m/s
E) kg.m/s

Question

What is the momentum of an electron whose kinetic energy equals its rest mass,m?
A)0.5 mc kg.m/s 
B) kg.m/s 
C) kg.m/s 
D) kg.m/s 
E) kg.m/s

Quizplus · Accepted Answer

The momentum of an electron is given by the formula: 
p=sqrt(2mK)
where m is the rest mass and K is the kinetic energy.
Since we are given that the kinetic energy equals the rest mass, we can substitute m for K in the above formula and get:
p=sqrt(2m^2)
simplifying this gives us:
p=m*sqrt(2)
Using the value of the rest mass of an electron (9.11x10^-31 kg), we get:
p=9.11x10^-31 * sqrt(2)
p=11.3x10^-31 kg m/s
which is closest to option B (11eaa331_f59d_8f12_9fad_4bebe25a2c62_TB6079_11 kgF1F1F1S1F1F1F10m/s)

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