Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: One Dimensional Motion Homework

  1. Sep 11, 2011 #1
    1. The problem statement, all variables and given/known data

    A person travels by car from one city to another with different constant speeds between pairs of cities. She drives for 45.0 min at 55.0 km/h, 17.0 min at 65 km/h, and 60.0 min at 30.0 km/h, and spends 55.0 min eating lunch and buying gas.
    (a) Determine the average speed for the trip.
    (b) Determine the distance between the initial and final cities along this route.

    2. Relevant equations

    I am having considerable difficulty getting started can you go cover the basics as intrinsically as possible this is my first corse in physics and only my third corse in science (I took a year of basic biology and chemistry) I have been given three formulas on average motion and instantaneous motion do these apply? I also have covered the velocity, acceleration, and change in position formula .. any help would be greatly appreciated so that I may understand and complete the rest of my homework on my own thank you in advance

    3. The attempt at a solution

    So far I have no attempted solutions I don't fully understand the question being asked to be frank. I tried taking the average of all the speeds but the we bite where I submit homework told me it was incorrect .. I have a feeling I first have to find the distance traveled how would that be done and do I need to convert units? again any help would be greatly appreciated thank you!
  2. jcsd
  3. Sep 11, 2011 #2


    User Avatar
    Homework Helper
    Gold Member

    Hello, CladeT Welcome to PF!
    Please read you book, visit a few websites, and do check out this site's Learning Materials. I would, but I'm in the middle of changing out a rusted garbage disposal :yuck:, otherwise I would have more time for that :wink:.

    That's okay, understanding will come with time. Let's look at a). What are they asking for? They are looking for average speed. What formulas or definitions do you have for this?
  4. Sep 11, 2011 #3
    Velocity = Displacement/Time

    I would reference my book but at the moment it is in the mail and the only online sources I have found show examples of this problem when you are given the distance and time not the speed and distance. Good luck with the garbage disposal I can't claim to be envious of you at the moment haha
  5. Sep 11, 2011 #4
    Thank you for your time also it is greatly appreciated
  6. Sep 11, 2011 #5


    User Avatar
    Homework Helper
    Gold Member

    If you do a search on "average speed definition" (not velocity!) you get "the total distance traveled divided by the time required to travel that distance".

    See if that helps you.
  7. Sep 11, 2011 #6
    Thank you for your time and not making a mockery of how vapid I was. I did intact use that formula the first time I worked through this problem but instead of converting the time i divided by to minutes I left it in hours. No wonder the results were so confusing. I appreciate your and hope the garbage disposal is once again operational.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook