Verifying an Electron's Final Speed After Releasing from Rest

AI Thread Summary
The problem involves calculating the final speed of an electron released from rest between two positive point charges. Using the conservation of energy principle, the equation Ek(f) + U(f) = Ek(i) + U(i) was applied to find the final speed when the electron is 10.0 cm from charge 1. The calculated final speed was 7.53 x 10^6 m/s. Despite initial concerns about the high speed, the answer was confirmed to be correct. The discussion highlights the importance of verifying calculations in physics problems.
rowkem
Messages
48
Reaction score
0

Homework Statement



Two stationary positive point charges, charge 1 of magnitude 3.45 nC and charge 2 of magnitude 1.85 nC, are separated by a distance of 50.0 cm. An electron is released from rest at the point midway between the two charges, and it moves along the line connecting the two charges.

What is the speed v(final) of the electron when it is 10.0 cm from charge 1?

Homework Equations



Ek= (mv^2)/2
U= (k(q1q2))/r

The Attempt at a Solution

I used the following equation:

Ek(f)+U(f) = Ek(i)+U(i)

(mv(f)^2)/2 + (k(q1q2))/r = (mv(i)^2)/2 + (k(q1q2))/r

(9.1x10^-31)(vf)^2)/2 + (((9x10^9)(3.45nC)(-1.6x10^-19))/0.10m) + (9x10^9)(1.85nC)(-1.6x10^-19))/0.40m) = (((9x10^9)(3.45nC)(-1.6x10^-19))/0.25m) + (9x10^9)(1.85nC)(-1.6x10^-19))/0.25m)

v(f) = 7.53 x 10^6 m/s

---------------------------------------------

So that's my answer. I lose marks if I submit an incorrect answer. That said, I just want to double check my answer before submitting it. A simple yes or no will suffice. Thanks in advance.

---------------------------------------------

That seems unreasonably high. Maybe I'm just ignorant but, guess we'll see.
 
Physics news on Phys.org


Took a stab at it. Was correct. Thanks everyone.
 
Kindly see the attached pdf. My attempt to solve it, is in it. I'm wondering if my solution is right. My idea is this: At any point of time, the ball may be assumed to be at an incline which is at an angle of θ(kindly see both the pics in the pdf file). The value of θ will continuously change and so will the value of friction. I'm not able to figure out, why my solution is wrong, if it is wrong .
TL;DR Summary: I came across this question from a Sri Lankan A-level textbook. Question - An ice cube with a length of 10 cm is immersed in water at 0 °C. An observer observes the ice cube from the water, and it seems to be 7.75 cm long. If the refractive index of water is 4/3, find the height of the ice cube immersed in the water. I could not understand how the apparent height of the ice cube in the water depends on the height of the ice cube immersed in the water. Does anyone have an...
Back
Top