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How much of a head start does B need to win the race?

  1. Apr 11, 2015 #1
    Hey all. Simple problem here. 2 people are running at 2 different speeds in a race 50m long (A at 5 m/s B at 3 m/s), A is clearly going to win, How much of a head start would B need to win?
    (This isn't a homework problem i'm just wondering how long I have to wait for my movie to buffer before I should start watching it.)
     
    Last edited: Apr 11, 2015
  2. jcsd
  3. Apr 11, 2015 #2
    Min 20 metres.
     
  4. Apr 11, 2015 #3
    Min?? Working out?
     
  5. Apr 11, 2015 #4
    Minimum of 20 metres.
     
  6. Apr 11, 2015 #5
    let the headstart be denoted by' x' and time taken to complete the race be 't'. Note that time will be same for A and B. Now, using the fact that
    Distance travelled = Speed* time, we have
    For A, 50= 5*t
    For B, 50=x + 3*t
    Solve these to get x=20, t=10
     
  7. Apr 11, 2015 #6
    Thanks
     
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