1. Not finding help here? Sign up for a free 30min 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!

Momentum Lab Help

  1. Jan 15, 2007 #1
    1. The problem statement, all variables and given/known data
    The other day, I was asked to conduct an experiment involving momentum. Basically, I set two mini-carts bumper to bumper, and hit a switch that caused them to push away from each other and travel in opposite directions. We then had to repeat the experiment using different weights and such.

    Anyway, after collecting the data, my physics teacher wants us to find the force of friction, coefficient of friction, and work done by friction. How do I approach these questions? I already know the carts’ Acceleration, Distance, Time, Initial Velocity, Final Velocity, Mass, Normal Force, and Momentum. Also, is acceleration supposed to be negative in these situations?

    2. Relevant equations

    Momentum = Mass * Velocity
    Coefficient of Friction = Normal Force * Force of Frction
    Friction = Force Applied from X Direction * (mass * acceleration)

    3. The attempt at a solution

    Fn - f = (mass x acceleration)
    :18N - f = 1.8kg x -.106m/s^2 ?
    ::-f = -18
    :::f = 18 N

    Thanks for the help!
     
  2. jcsd
  3. Jan 15, 2007 #2

    cristo

    User Avatar
    Staff Emeritus
    Science Advisor

    No your calculation isn't correct. After the cart has been pushed, there is only one force acting on it. What do you think this is? This should answer your question about negative acceleration, and enable you to use Newton's second correctly.
     
  4. Jan 15, 2007 #3
    Well, the only force acting on the carts after the push is Friction. I'm guessing since it's slowing the cart down, the force is negative - as it opposes forward progress. So, would friction be equal to (mass * -a)?
     
  5. Jan 15, 2007 #4

    cristo

    User Avatar
    Staff Emeritus
    Science Advisor

    Correct. So, you now have the magnitude of friction. Can you calculate the coefficient and work done?
     
  6. Jan 15, 2007 #5
    I believe so. All I have to do is plug the Force of Friction into the "Coefficient of Friction = Normal Force * Force of Friction, correct? :)
     
  7. Jan 15, 2007 #6

    cristo

    User Avatar
    Staff Emeritus
    Science Advisor

    Well, the correct equation is force of friction=coefficient * normal force. But yes you just plus in the values you know.
     
  8. Jan 15, 2007 #7
    Oh okay. Thanks for all the help, I really appreciate it!

    Have a nice day. :-)
     
  9. Jan 15, 2007 #8

    cristo

    User Avatar
    Staff Emeritus
    Science Advisor

    You're welcome!
     
  10. Jan 15, 2007 #9
    Apparently, there is another question that asks, "What was the momentum of the system after collision?". What does my teacher mean when he says "momentum of the system"? Is it the average Momentum from both carts?
     
    Last edited: Jan 15, 2007
  11. Jan 15, 2007 #10

    cristo

    User Avatar
    Staff Emeritus
    Science Advisor

    Total momentum of the system will be the sum of the momenta of the two carts.
     
  12. Jan 15, 2007 #11
    Allrighty, thanks again!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Momentum Lab Help
  1. Help on a Momentum Lab (Replies: 1)

  2. Momentum Lab - Help! (Replies: 0)

Loading...