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## Homework Statement

An electron with rest mass m0 = 9.11E10-31 kg and charge e= 1.6E10-19 C was accelerated with an acceleration voltage U=30 kV

a) What is its velocity , momentum and energy in a classical picture ?

b)What is its velocity , momentum and energy in a relativistic picture ? What is its relativistic mass ?

c) If the acceleration voltage was only U=30 V , What is the electron's velocity , momentum and energy ? Would you use the classical or the relativistic picture and why ?

## Homework Equations

For Part a) v = dx / dt

p = mv

energy = (1/2) m0 * v2

For Part b) Lorentz Transformation for Velocity

ux' = [ux - v] / [ 1+ (vux /c^2) ]

Where ux' as i understand is the velocity , moving frame of reference .

Relativisitc momentum

p= m0 * u / ((1-(u^2/c^2))^1/2

Relativistic Energy

E=mc^2

Relativisitic mass

mr = m0 / ((1-(u^2/c^2))^1/2

## The Attempt at a Solution

If the above equations are correct in this case so

For part a) for velocity i m not getting how can i calculate the numerical figure

for momentum offcourse if i have velocity i can simply put it in the equation

for energy as well i need velcocity

For part b)

for velocity what is the difference in Ux and V ?

What U i have to substitute for relativistic momentum ?

For Energy :

mass = 9.11 E 10 -31

For Relativistic mass

m0 = 9.11 E 10 -31

Thanks in advance