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

Increasing speed by 5 mph saves 10 mins?

  1. Nov 8, 2006 #1
    If a person drives the same distance twice, and saves 10 mins by driving 5mph more the second time, what is the distance and the speeds?
  2. jcsd
  3. Nov 8, 2006 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Speed * time = distance.

    Set up two equations -- one for each trip -- and notice that the distances are equal. Thus, you can set the equations equal to each other, arriving at:

    Speed1 * time1 = speed2 * time2.

    You know that speed2 = speed1 + 5, and that time2 = time1 - 10.

    Put these equations together and solve for distance...

    - Warren
  4. Nov 8, 2006 #3
    Can you work through it for me? I keep getting time1=10+2*speed1...
  5. Nov 9, 2006 #4


    User Avatar

    Staff: Mentor

    Write out your full two equations and show how you are trying to solve them.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook