1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Finding time it takes for electron to travel a certain distance

  1. Jun 18, 2014 #1
    1. The problem statement, all variables and given/known data
    Over a distance of 3 cm an electron accelerates uniformly from a speed of 9 x 103 m/s to a speed of 6 x 106 m/s. How long does it take the electron to cross this distance?

    2. Relevant equations

    d = 1/2(v0 + v)t

    3. The attempt at a solution

    Find t:

    d = 3 cm /10 cm = 0.3 m
    2 d / v0 + v = t

    2 (0.3 m) / (9 x 103 m/s + 6 x 106 m/s) = t

    This is where I got a little lost, especially with trying to do it on paper as I'm not able to use a calculator for the test.
  2. jcsd
  3. Jun 18, 2014 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Umm.. how many cm to the m?
    First, there's a simple cancellation out of a factor. If you then write out the denominator in fixed point, what do you notice?
  4. Jun 18, 2014 #3


    User Avatar
    Gold Member

    Average speed is V = 600900000/2 =300450000 cm
    time is 3 /V = 3/30045 (*10000) can you do 3.00000/30045 on paper? and then 0.00000000....
    Last edited: Jun 18, 2014
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted