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: Average acceleration problem

  1. Nov 19, 2011 #1
    1. The problem statement, all variables and given/known data

    The average speed of a nitrogen molecule in air is about 6.70 multiplied by 102 m/s, and its mass is about 4.68 multiplied by 10-26 kg.

    (a) If it takes 1.80 multiplied by 10-13 s for a nitrogen molecule to hit a wall and rebound with the same speed but moving in an opposite direction (assumed to be the negative direction), what is the average acceleration of the molecule during this time interval?

    (b) What average force does the molecule exert on the wall?

    2. Relevant equations
    I have no idea

    3. The attempt at a solution
    I dont even know how to attempt
  2. jcsd
  3. Nov 19, 2011 #2


    User Avatar
    Homework Helper

    We can't help much without seeing some effort from you.
    It is accelerated motion. Have you any formulas for accelerated motion? Look for one with a change in velocity, Δv or Vf - Vi in it because you are given those values.
  4. Nov 19, 2011 #3
    Obviously I've already exhausted all the resources I have and all the methods I've tried do not work or else I would not be here...the only formula I have with that is v^2-v_0^2=2a(x-x_0) but I dont have x...not sure what v and v_0 are either..
  5. Nov 19, 2011 #4


    User Avatar
    Homework Helper

    There is a decent set of equations here: http://hyperphysics.phy-astr.gsu.edu/hbase/acons.html

    Note that it uses V and Vo instead of Vf and Vi.
    It says "acceleration is the slope on the velocity graph", which means a = Δv/Δt, a nice variation on the formulas it has with the V and Vo. Think of Δv as Vf - Vi. And Δt is just t if you are starting out at time zero.

    There is a nice set of formulas and their derivations here:
    Last edited: Nov 19, 2011
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook