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!

Help with kinematics

  1. Sep 17, 2007 #1
    1. The problem statement, all variables and given/known data

    A sailboard is sailing at 6.5 when a gust of wind hits, causing it to accelerate at 0.48 at a 35 angle to its original direction of motion.

    If the acceleration lasts 6.3 , what is the board's net displacement during the wind gust?

    2. Relevant equations

    Ok so far, I have drawn all of the motion graphs.
    So I got

    X Y

    X_0= 0m Y_0= 0m
    X_F=? Y_F=?
    V_0x= 6.5m/s v_oy=0m/s
    V_fy= 6.5m/s v_fy=?
    a= 0 m/s^2 a= .48m/s^2
    t= 6.3secs t=6.3secs

    3. The attempt at a solution

    And assuming those are correct. I got v_fy= 4.55 m/s by using 6.5tan35 = v_fy

    then I used this equation: x=x_0+v_ot+(1/2)at^2 and got

    X_f= 40.95m
    Y_f= 9.5m
    And then I added them together and then its 50.45m??? Is this correct, because online it said it was wrong?

    Thanks for helping!
  2. jcsd
  3. Sep 17, 2007 #2


    User Avatar
    Homework Helper

    suppose it's initially moving eastbound at 6.5m/s. ie: northbound velocity = 0.

    so acceleration 0.48m/s^2 east 30 degrees north.

    What is the component of acceleration in the east/west direction?

    What is the component of acceleration in the north/south direction?

    So you can divide the problem into the east/west part (to get the displacement east/west), and the north/south part (to get the displacement north/south)... and work them separetly... each part is a uniform acceleration problem.
  4. Mar 7, 2010 #3
    Need help with kinematics

    I figured out this problem:

    You step off a cliff 30 meters high.
    A. How long will it take to hit the water below?
    t^2= 6.122
    t= 2.47

    B. What is your velocity (mph) when you hit the water?
    Vty= Voy-9.8t
    Vty=-24.25 m/s = 54.223 mph

    Can anyone help me solve this one, based on the above problem?:

    2. How high would the cliff have to be in 1. above if your velocity hitting the water was 100 mph?

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

Have something to add?

Similar Discussions: Help with kinematics
  1. Help with kinematics (Replies: 1)

  2. Kinematic help (Replies: 4)

  3. Kinematics help (Replies: 12)

  4. Help With Kinematics! (Replies: 1)

  5. Kinematics HELP (Replies: 1)