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!

Average speed

  1. Mar 1, 2013 #1
    A person walks first at a constant speed of 5.00 m/s along a straight line from point A to point B and then back along the line from B to A at a constant speed of 3.00 m/s. What are (a) her average speed over the entire trip and (b) her average velocity over the entire trip?

    I already solved this problem but I think I had to think way outside the box for it so I want to see an easier way to figure this out. For part "(b)", I just wrote as the answer 0 m/s because she ends up in the same spot. I'm not going to talk about "(a)" because I do not want to disrupt peoples problem solving process. I also want to know if it is correct to use 0 m/s rather than 0; I think it is because 0 pressure is not the same as 0 m/s.

    Another thing I want to know is why does dividing the sum of the speeds by 2 not work since it is average speed? I think it is because the it took longer travel at 3.0 m/s. And this affects the results because their are two different times to add to eachother.
     
  2. jcsd
  3. Mar 1, 2013 #2

    cepheid

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    For part a, average speed is total distance over total time. The key to the problem is just setting the unknown distance between point A and point B as a variable "d". Use the relation distance = speed*time to find the time required to travel each leg of the journey (in terms of d). You will find that this variable d cancels out in the final answer for v.


    Yes, physical quantities have dimension, and you must include units when expressing them.

    Yes, your reasoning is correct.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Average speed
  1. Average speed (Replies: 6)

  2. Average speed (Replies: 3)

  3. Average speed (Replies: 1)

  4. Average speed (Replies: 2)

Loading...