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!

A car is moving by gravity force

  1. Sep 29, 2012 #1

    1f5

    User Avatar

    1. The problem statement, all variables and given/known data

    In t=0 a car is free from it's chain and can fall freely through a inclined plane (10 degrees)
    rear wheels weight 500 lb each one and have an diameter of eight feet. Front wheel weights 800 lb and have a radius of 2 feet. The body of vehicle weights 9000 lb. Assume that wheels can drift. Obtain a expression for velocity in function of time.

    2. Relevant equations

    Summation of forces = ma
    We have inerce forces and gravity force. gravity force exerted on vehicle equals to Mgsin10


    3. The attempt at a solution
    inertia force formula is Ia, then I should add the forces.


    M*g*sin(10)+Ialpha=Ma
    5.591471 ft/s^2+Ialpha/M=a
    alpha is angular acceleration.
    A condition for simultaneous rotation and translation movement is v=wr
    w=v/r
    dw/dt= 1/r(dv/dt)
    5.591471M+I(1/r) dv/dt=Mdv/dt
    and Inertia applies for each rotating element
    5.6M+(I1/r1+I2/r2) dv/dt=Mdv/dt
    5.6M+(I1/4+I2/2)dv/dt=Mdv/dt

    Moment of inertia for a wheel=mr^2/2.
    M is the total mass in the system.
    5.6M+(mr^2/2+md^2)/4+ (m1r1^2/2+md2^2)/2))dv/dt=Mdv/dt
    5.6M+( (8m+md^2)/4+(2m1+md2^2)/2)dv/dt=Mdv/dt
    5.6M+( (8000+1000d^2)/4+(1600+800d2^2)/2)dv/dt=Mdv/dt

    D are distances from the axis, they are unknown.
    I only should put the expression from dv/dt and integrate for get a expression for v in function of t.

    I don't know if my solution is right/
    In which step I am wrong?
     
  2. jcsd
  3. Sep 29, 2012 #2

    1f5

    User Avatar

    Well, after a few hours I have noticed my mistake.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: A car is moving by gravity force
Loading...