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!

Conservation of momentum and energy

  1. Oct 19, 2009 #1
    1. The problem statement, all variables and given/known data
    a) At t=1 second, a 0.5 kg cart is at x=0.5 m, traveling at 0.5 m/s. At t=3 seconds, the cart is
    at 1.4 m, traveling at 0.4 m/s. What is the acceleration due to friction, the frictional force and
    the work done by friction? What is the change in kinetic energy of the cart?
    b) If a cart of mass 0.6 kg, traveling a 0.5 m/s collides elastically with a cart of mass 0.4 kg,
    initially at rest, what is the final velocity of the first cart?
    c) If the two carts above stick together after the collision, what is the final velocity of the first
    cart?
    d) What is the final velocity of the first cart in (b) if the second cart has mass 1.5 kg?
    e) What is the final velocity of the first cart in (c) if the second cart has mass 1.5 kg?



    2. Relevant equations
    Elastic collison formula
    Inelastic collision
    Impulse
    W=-FD
    Change in kinetic energy formula

    3. The attempt at a solution
    ok here is my attempt. I need someone to check if Im using the right equation for each problem.

    part a)
    i used vf^2-vi^2 = 2ad
    to get an acceleration of .05

    To find the firctional force i used
    F = -ma F= (.5)(.05)
    Ff = -.025N

    work done by friction
    W = -Fd
    W =-(-.025)(.05)
    W = 0.0125J

    change in ke
    Ke =1/2mvf^2-1/2mvi^2
    KE=1/2(.5)(0.5)^2-.5(0.5)(0.4)^2
    Kef = .0225



    part b)
    v1f = vi*(m1-m2)/(m1+m2)
    0.5*(0.6-0.4)/(0.6+0.4)
    v1f=0.1m/s

    part c)
    v1f = vi*(m1)/(m1+m2)
    (0.5)(.6)/(0.6+0.4)
    v1f=0.3m/s


    part d
    v1f = vi*(m1-m2)/(m1+m2)
    0.5*(0.6-1.5)/(0.6+1.5)
    v1f=0.2143m/s


    part e

    v1f = vi*(m1)/(m1+m2)
    (0.5)(.6)/(0.6+1.5)
    v1f=0.143m/s
     
  2. jcsd
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted