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Finding Impulse and Magnitude

  1. Mar 31, 2015 #1
    1. The problem statement, all variables and given/known data

    http://i.imgur.com/COAuag8.png

    2. Relevant equations

    Change of momentum and Force = impulse / time.

    3. The attempt at a solution

    I got 0.325204kg m/s for magnitude of the impulse

    and 8.338572195N for average force exerted by the ball on the wall.

    (0.00063)(26.6)(cos14)-(-0.0063)(26.6)(cos14))
    = 0.325204kg m/s

    Force = impulse / time

    0.325204/ 0.039
    = 8.338572195 N

    Why is my answer incorrect? This is frustrating been trying to solve this for 1 hour now which is way too long for 1 question.

    Please check the imgur I just hate online homework especially for physics/math, because some websites are weird and gives me incorrect answers if I forget a space bar between meter and seconds (extremely dumb) while other times the question does not care or if it's not to the maximum decimal places where margin of error is 0.0000000001 or 0.1% (depends on the professors mood).

    Thanks in advance for your help and the removal of my headache.
     
  2. jcsd
  3. Mar 31, 2015 #2
    You are to calculate for moment and not for force.
     
  4. Mar 31, 2015 #3
    Oh didn't realise it. Anyway since there is only a change in horizontal velocity and hence momentum due to the elastic collision, you will need to resolve the velocity component and get the impulse from it.

    From your solution, the no. one problem is with the conversion of the mass to kilogrammes. No. 2 is the use of the wrong trigonometric ratio.
     
  5. Mar 31, 2015 #4
    impulse = change in momentum = force*Δt
     
  6. Mar 31, 2015 #5
    I still don't get it? What formula should I because another guy said impulse = change in momentum = force (change in time)?

    I'm extremely confused now

    Edit:


    (0.0063)(26.6)(cos 14)-(0.0063.........)
    Same as 2(0.0063)(26.6)(cos14)
    =0.3252043156 Kg*m/s


    Force = Impulse / time

    =0.3252/0.039= 8.33846 N
     
    Last edited: Mar 31, 2015
  7. Mar 31, 2015 #6
    Try cos(76 deg) that might help

    upload_2015-3-31_17-7-48.png

    Do you see why??
     

    Attached Files:

  8. Mar 31, 2015 #7
    I FEEL EXTREMELY STUPID AFTER YOU POINTED THAT OUT.

    I am so mad at myself!!!((#(##(@@*@*@!(!!)@@

    Thanks though.
     
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