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!

Acceleration/ equation problem

  1. Sep 29, 2008 #1
    1. An electron of mass 9.11×10^−31 kg leaves one end of a TV picture tube with zero initial speed and travels in a straight line to the accelerating grid, which is a distance 1.20 cm away. It reaches the grid with a speed of 4.50×10^6 m/s. The accelerating force is constant.
    Find the acceleration.
    Find the time to reach the grid.
    Find the net force. (ignore gravity on the electron)

    2. v^2=(u^2)+2*a*s

    3. I plugged in the numbers to the equation v^2=(u^2)+2*a*s. to find acceleration, but the anwer (1.875*10^8) was incorrect. Is this the correct equation? The other answers should stem from the acceleration right?
  2. jcsd
  3. Sep 29, 2008 #2


    User Avatar
    Homework Helper

    (4.50×10^6 m/s.)^2 = 2*a*(1.2x10^-2)
    From the above equation find the value of a
  4. Sep 29, 2008 #3
    Acceleration - Sub into equation v2=u2+2aS -- make sure you only substitute after converting to SI units.

    Time - Use Equation a=(v-u)/t (Yes you need to find acceleration first)

    Net force - Use equation [tex]\sum[/tex]F=ma

    And 1.875*10^8 for acceleration is wrong.

    Hope this helps.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook