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Problem finding time, position, and velocity

  1. Jul 23, 2016 #1
    1. A bicyclist is finishing his repair of a flat tire when his friend rides by at 3.0 m/s. Two seconds later, the bicyclist hops on his bike and accelerates at 2.2m/s^2 until he catches his friend.
    A) how much time does it take until he catches his friend?
    B) how far had he traveled in this time?
    C) what is his speed when he catches up?



    2. I have tried using the three equations for velocity and position but hav not came up with anything that is close to correct. I know the values have to work in the equations somehow! :(


    3. The attempt at a solution
     
  2. jcsd
  3. Jul 23, 2016 #2

    QuantumQuest

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    Gold Member

    What are the equations you have used so far? Please write them down. According to the problem data, have you any idea of how to combine them in order to find what is asked?
     
  4. Jul 23, 2016 #3
    Vf=Vi+AT
    Xf=Xi+ViT+1/2AT^2
    Vf^2=Vi^2+2A(Xf-Xf)

    Vi is the initial velocity
    Vf is the final velocity
    Xi is the initial position
    Xf is the final position
    A is acceleration
    T is time

    I have tried drawing mutiple diagrams and labeling everything I possibly can. I have come up with his starting position as 0 his initial velocity as 0 his acceleration is 2.2m/s^2 I am not given his final position or final velocity. Also his friend has a constant velocity of 3.0m/s so his acceleration is zero. i suppose the 3.0m/s would be his friends initial velocity and his final velocity.
    I guess the biggest problem I am having is trying to properly label every thing and be able to plug the values into the equations to figure out the missing information. This problem has had me stumped for hours now.
     
  5. Jul 23, 2016 #4

    gneill

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    Staff: Mentor

    Start by listing the known things at the instant the first cyclist sets off. For example, what is the speed and position of the second cyclist at that instant? Write an equation that predicts his position from that moment onward (that is, start counting time from that instant). Do the same for the second cyclist (the one who is accelerating).
     
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