Electrical Potential and Potential Difference?

Question

(a) Calculate the speed of a proton that is accelerated from rest through a potential difference of 120V. (b) Calculate the speed of an electron that is accelerated through the same potential difference.

Thanks d*ck. No matter, I figured it out.

Answer 1

Ok, use the conservation of the energy :

the electrical energy at the beginning must be equal when the proton gains the speed.

electrical energy = q*V

kinetic energy = m*v^2 / 2

mass of the proton = 1840*9.1*10^-31 kg

(1.6*10^-19)*120 = 1840*9.1*10^-31*v^2 / 2

v = speed

0.02*10^12 = v^2

v = 0.14*10^6 m/s

b) For the electron :

mass of the electron = 9.1*10^-31 kg

-q*v = -m*v^2 / 3

why minus ?, because the electron has a minus chargen and the electron will move to the opposite direction

1.6*10^-19*120 = 9.1*10^-31*v^2 / 2

v^2 = 42.19*10^12

v = 6.5*10^6 m/s

Hope that might help you