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!

Collision between two cars

  1. Nov 24, 2009 #1
    1. The problem statement, all variables and given/known data

    The driver of a 3850 lb Pontiac traveling East at 32 miles/hr has a collision with a 3100 lb Toyota traveling East at 24 miles/hr. The coefficient of restitution is .27. Find:
    i) The final speed of the Pontiac after the collision
    ii) The final speed of the Toyota after the collision

    3850lb = 1744kg
    3100lb = 1404kg
    32 miles/hr = 46.93 ft/s
    24 miles/hr = 35.2 ft/s
    Cr = .27


    2. Relevant equations

    I'm attempting to solve i) and ii) using the equation:

    e616cb918a63fca97cdfb47072e9d0e8.png

    3. The attempt at a solution



    I need to do the work in ft/s & kg



    Appx - 40.26 ft/s for m1'
    Appx - 43.45 ft/s for m2'


    Does it look right for this type of problem?

    iii) The kinetic energy lost in the collision

    KE = (1/2)(m)(v2 )

    KE (m1) = (1/2)(1744kg)(14.3m/s)2
    KE (m1') = (1/2)(1744kg)(12.27m/s)2
    KE (m2) = (1/2)(1404kg)(10.73m/s)2
    KE (m2') = (1/2)(1404kg)(13.24m/s)2

    KE (m1) appx = 178315
    KE (m1') appx = 131644
    KE (m2) appx = 80823
    KE (m2') appx = 123058

    (178315+80823) - (131644+123058)

    4436 Joules lost :)

    iv) Suppose the cars locked together during the collision. Find the final speed of the 2 cars after collision for this case

    7909bbd935e5d7aa3e71b4ea41703c06.png

    1744kg*46.93ft/s+1404kg*35.2ft/s
    3148kg

    = 41.7 ft/s
     
    Last edited: Nov 24, 2009
  2. jcsd
  3. Nov 24, 2009 #2

    Redbelly98

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Re: Collisions

    Looks good. I haven't checked your arithmetic in detail, but your method looks sound.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Collision between two cars
Loading...