An electron is moving east in a uniform electric field of 1.45 N / C directed to
ID: 1528848 • Letter: A
Question
An electron is moving east in a uniform electric field of 1.45 N/C directed to the west. At point A, the velocity of the electron is 4.50×105 m/s pointed toward the east. What is the speed of the electron when it reaches point B, which is a distance of 0.390 m east of point A? ANSWER: 6.34*10^5 PLEAS ANSWER PART B A proton is moving in the uniform electric field of part A. At point A, the velocity of the proton is 1.93×104 m/s again pointed towards the east. What is the speed of the proton at point B?
again pointed towards the east. What is the speed of the proton at point B?8
Explanation / Answer
Force acting on the electron is F = q*E = 1.6*10^-19*1.45 = 2.32*10^-19 N along east
but F = m*a = 2.32*10^-19
accelaration is a = (2.32*10^-19)/(9.11*10^-31) = 2.54*10^11 m/sec^2 along east
displacement is S = 0.39 m
initial speed is Vo = 4.5*10^5 m/sec
Using kinematic equations
V^2-Vo^2 = 2*a*S
V^2- ( 4.5*10^5)^2 = 2*2.54*10^11*0.39
V = 6.34*10^5 m/sec
B) for proton
a = F/m = (2.32*10^-19)/(1.67*10^-27) = 1.38*10^8 m/sec^2 along west
Using kinematic equations
V^2 -Vo^2 = 2*a*S
V^2 - (1.93*10^4)^2 = -2*1.38*10^8*0.39
V = 1.63*10^4 m/sec is the speed of the proton at B
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