Facebook Page
Twitter
RSS
Thanks Thanks:  0
+ Reply to Thread
Results 1 to 3 of 3
  1. MHB Apprentice

    Status
    Offline
    Join Date
    Jun 2015
    Posts
    19
    Thanks
    11 times
    Thanked
    11 times
    #1
    H=16t-1.86t^2 is the height formula. The ball was thrown 16 m/s.

    I derived 16-3.72a.

    When will the rock hit the surface. It hits the surface 8.6 seconds.

    What velocity does the rock hit the surface? H=0.0344 then the velocity is 15.87 m/s?






    This is what I chose.

    [-4.-2)
    (-2,2)
    [2,4)
    (4,6)
    (6,8)
    Last edited by tc903; June 23rd, 2015 at 13:28.

  2. # ADS
    Circuit advertisement
    Join Date
    Always
    Posts
    Many
     

  3. MHB Master
    MHB Site Helper
    MHB Math Helper
    MHB Ambassador
    Sudharaka's Avatar
    Status
    Offline
    Join Date
    Feb 2012
    Location
    Canada
    Posts
    1,620
    Thanks
    7,514 times
    Thanked
    2,543 times
    Thank/Post
    1.570
    Awards
    University POTW Award (Jan-June 2013)
    #2
    Quote Originally Posted by tc903 View Post
    H=16t-1.86t^2 is the height formula. The ball was thrown 16 m/s.

    I derived 16-3.72a.

    When will the rock hit the surface. It hits the surface 8.6 seconds.

    What velocity does the rock hit the surface? H=0.0344 then the velocity is 15.87 m/s?






    This is what I chose.

    [-4.-2)
    (-2,2)
    [2,4)
    (4,6)
    (6,8)
    Hi tc903,

    I think the velocity is wrong. Since $H=16t-1.86t^2$ we have, $\frac{dH}{dt}=16-3.72t$. The rock reaches the ground at $t=8.6$ and therefore the velocity is, $\left.\frac{dH}{dt}\right|_{t=8.6}=16-3.72(8.6)=-15.992$.

  4. MHB Apprentice

    Status
    Offline
    Join Date
    Jun 2015
    Posts
    19
    Thanks
    11 times
    Thanked
    11 times
    #3 Thread Author
    I would think the same, maybe I shouldn't have rounded it to -15.9 when I originally did that way. I have a computer that is telling me no when I plug in an answer like that.

Similar Threads

  1. How to find the answer sin 120.
    By tmt in forum Trigonometry
    Replies: 1
    Last Post: June 17th, 2015, 16:18
  2. Answer Game
    By soroban in forum Chat Room
    Replies: 0
    Last Post: October 17th, 2013, 19:25
  3. Is one form of the answer more right than the other
    By find_the_fun in forum Basic Probability and Statistics
    Replies: 1
    Last Post: October 17th, 2013, 03:22
  4. The most appropriate answer...
    By chisigma in forum Chat Room
    Replies: 15
    Last Post: March 25th, 2012, 22:04
  5. Bug with quick answer
    By Markov in forum Questions, Comments, and Feedback
    Replies: 4
    Last Post: February 2nd, 2012, 15:26

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Math Help Boards