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!

Speed physics homework

  1. Jan 22, 2009 #1
    1. The problem statement, all variables and given/known data
    Can you help me answer this question?

    Paolo and some friends want to order a take away. Paolo writes down what they need to know about the two nearest takeaways:

    Ludo's Pizza:
    Time to cook food is 1/4 hour
    Distance to the house is 6.5 KM
    Deliver on scooters with average speed of 30km/h

    Moonlight Indian Takeaway:
    Time taken to cook food is 1/2 hour
    Distance to house is 4km
    Delivery van has average speed of 40km/h

    Which takeaway should they order from to get their food quickest? (please show working)


    2. Relevant equations
    s=d/t


    3. The attempt at a solution
    I've tried converting each variable to metres and minutes but I couldn't work it out.
     
    Last edited by a moderator: Mar 7, 2013
  2. jcsd
  3. Jan 22, 2009 #2

    Borek

    User Avatar

    Staff: Mentor

    Re: Speed

    Calculate time required to deliver the pizza once it is ready.
     
  4. Jan 22, 2009 #3

    rl.bhat

    User Avatar
    Homework Helper

    Re: Speed

    Find the time taken by the scooter to cover 6.5 km and van to cover 4 km. Add to them the respective time of cooking.
     
  5. Jan 22, 2009 #4
    Re: Speed

    Yeah, but how?
     
  6. Jan 22, 2009 #5

    Borek

    User Avatar

    Staff: Mentor

    Re: Speed

    Imagine you are riding on the bike at 10 mph. You are 5 miles from home. How long will it take to get home?
     
  7. Jan 22, 2009 #6
    Re: Speed

    The First one is faster from what i worked out. it takes << answer deleted by berkeman >>.
     
    Last edited by a moderator: Jan 22, 2009
  8. Jan 22, 2009 #7
    Re: Speed

    You have the correct answer, first is faster, but I think the times you calculated are wrong
     
  9. Jan 22, 2009 #8

    Borek

    User Avatar

    Staff: Mentor

    Re: Speed

    Stratosphere: nobody asked you to do ViralRiver homework.
     
  10. Jan 22, 2009 #9
    Re: Speed

    I did T=r/d to calculate the time it takes for the moped to get to the house.
     
  11. Jan 22, 2009 #10
    Re: Speed

    Got confused there, thought Stratosphere had asked the question originally. ViralRiver already gave the relevent equation (s=d/t) you ( or ViralRiver really) need to rearrange that for t.
     
  12. Jan 22, 2009 #11
    Re: Speed

    This is what I got:

    Ludo - 0.47 hours (2dp)
    Moonlight - 0.6 hours

    Is this right?
     
  13. Jan 22, 2009 #12

    Borek

    User Avatar

    Staff: Mentor

    Re: Speed

    Looks OK :smile:
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?