Results 1 to 5 of 5

Math Help - [Kinematics] Don't know how to find value

  1. #1
    Junior Member Cthul's Avatar
    Joined
    Mar 2010
    Posts
    71

    [Kinematics] Don't know how to find value

    Crate is being lowered by a crane at a constant speed of 2 m/s when a ball falls out of the hole in the crate, it hits the floor 10s before the crate. Find the height of the crate when the ball fell out of the crate.

    How do I find the height?

    All formulas gave me 20 as the height.. which is wrong.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    12,062
    Thanks
    902
    Quote Originally Posted by Cthul View Post
    Crate is being lowered by a crane at a constant speed of 2 m/s when a ball falls out of the hole in the crate, it hits the floor 10s before the crate. Find the height of the crate when the ball fell out of the crate.

    How do I find the height?

    All formulas gave me 20 as the height.. which is wrong.
    let h = height of the crate when the ball drops out

    ball's initial speed = 2 m/s

    let t = time for the ball to hit the ground

    t+10 = time for the crate to hit the ground

    for the crate ...

     <br />
h = 2(t+10)<br />

    for the ball (using 10 for g) ...

     <br />
h = 2t + 5t^2<br />

     <br />
2t + 5t^2 = 2(t+10)<br />

    solve for t, then determine h
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member Cthul's Avatar
    Joined
    Mar 2010
    Posts
    71

    Help please

    Thanks skeeter. That helped, I got the right answer.

    I got more questions I do not understand.

    Edit: I forgot to specify what I'm actaully stuck on, the 5th question, where the skater is 2 seconds earlier than the cyclist. I'm just wondering how to put it on the graph. So, I assume SKATER: 160=12*22, is that right?

    A cyclist, passes the starting line t=0

    The cyclist reaches the finish at (t=22)

    What I have so far:
    1- the distance of the starting from the finish line
    260m

    2- the distance travelled after the finish line
    24m

    3- the acceleration of the cyclist
    -3ms^-2

    4- the average speed of the cyclist from the starting to finish
    10ms^-1

    5- A skater passed the starting line 2 seconds before cyclist. Skater is travelling at a constant speed of 11ms^-1. Who wins the race and how much?
    ?
    Last edited by Cthul; May 28th 2010 at 05:27 AM.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    skeeter's Avatar
    Joined
    Jun 2008
    From
    North Texas
    Posts
    12,062
    Thanks
    902
    Quote Originally Posted by Cthul View Post
    Thanks skeeter. That helped, I got the right answer.

    I got more questions I do not understand.

    Edit: I forgot to specify what I'm actaully stuck on, the 5th question, where the skater is 2 seconds earlier than the cyclist. I'm just wondering how to put it on the graph. So, I assume SKATER: 160=12*22, is that right?

    A cyclist, passes the starting line t=0

    The cyclist reaches the finish at (t=22)

    What I have so far:
    1- the distance of the starting from the finish line
    260m correct

    2- the distance travelled after the finish line
    24m correct

    3- the acceleration of the cyclist
    -3ms^-2 correct

    4- the average speed of the cyclist from the starting to finish
    10ms^-1 |v{avg}| = (260 m)/(22 s)

    5- A skater passed the starting line 2 seconds before cyclist. Skater is travelling at a constant speed of 11ms^-1. Who wins the race and how much? t = 260/11 = 23.6 s ... but he got a 2 second headstart, so the skater crosses the finish line at t = 21.6 s relative to when the cyclist started.
    ...

    next time, start a new problem with a new thread.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Junior Member Cthul's Avatar
    Joined
    Mar 2010
    Posts
    71
    Quote Originally Posted by skeeter
    ...

    next time, start a new problem with a new thread.
    Understandable. Thanks for the help. (Solved)
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Kinematics, find x given v.
    Posted in the Differential Equations Forum
    Replies: 11
    Last Post: December 7th 2010, 10:56 AM
  2. Kinematics
    Posted in the Calculus Forum
    Replies: 2
    Last Post: May 1st 2009, 04:45 PM
  3. Kinematics
    Posted in the Advanced Applied Math Forum
    Replies: 1
    Last Post: May 30th 2008, 11:39 AM
  4. Kinematics
    Posted in the Math Topics Forum
    Replies: 6
    Last Post: October 22nd 2007, 09:54 AM
  5. kinematics
    Posted in the Advanced Applied Math Forum
    Replies: 1
    Last Post: August 3rd 2006, 11:07 PM

Search Tags


/mathhelpforum @mathhelpforum