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!

Constant Acceleration Automobile

  1. Jan 23, 2008 #1
    [SOLVED] Constant Acceleration

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

    At the instant the traffic light turns green, an automobile starts with a constant acceleration a of 2.1 m/s^2. At the same instant a truck is 10.2 m down the road and traveling with a constant speed of 8.5 m/s. (a) How far beyond the traffic signal will the automobile overtake the truck? (b) How fast will the automobile be traveling at that instant?

    2. Relevant equations



    3. The attempt at a solution

    s(t) = 1/2 a * t^2 + v0 * t + s0
    a = acceleration
    v0 = initial speed
    s0 = initial position


    Being for the truck
    a = 0 m/s^2
    v0 = 8.5 m/s
    s0 = 10.2 m
    and being for the car
    a = 2.1 m/s^2
    v0 = 0 m/s
    s0 = 0 m
    the equation will be:
    8.5 m/s * t + 10.2 m = (There is a 1/2 here right?) (1/2)2.1 m/s^2 * t^2

    Solving this I get 9.156s which is apparently incorrect.
     
  2. jcsd
  3. Jan 23, 2008 #2

    G01

    User Avatar
    Homework Helper
    Gold Member

    I believe the equation you set up is correct. Can you show your math?
     
  4. Jan 23, 2008 #3
    Well the math is kinda already there QQ I just plugged it into quadratic equation.
     
  5. Jan 23, 2008 #4
    OK I got it!

    s(9.16) = 1/2 (2.1) * (9.16)^2 = 88.1 meters

    and after 9.16 seconds, it is traveling
    v = at
    v = 2.1(9.16) = 19.2 m/s
     
  6. Jan 23, 2008 #5

    G01

    User Avatar
    Homework Helper
    Gold Member

    Awesome! Good job!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Constant Acceleration Automobile
  1. Constant acceleration (Replies: 3)

  2. Constant Acceleration (Replies: 30)

Loading...