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!

Impulse with snowballs hitting a wall

  1. Nov 16, 2016 #1
    1. The problem statement, all variables and given/known data
    Two average forces. A steady stream of 0.250 kg snowballs is shot perpendicularly into a wall at a speed of . Each ball sticks to the wall. Figure 9-49 gives the magnitude F of the force on the wall as a function of time t for two of the snowball impacts. Impacts occur with a repetition time interval , last a duration time interval , and produce isosceles triangles on the graph, with each impact reaching a force maximum . During each impact, what are the magnitudes of (a) the impulse and (b) the average force on the wall? (c) During a time interval of many impacts, what is the magnitude of the average force on the wall?

    upload_2016-11-16_13-29-23.png
    2. Relevant equations


    3. The attempt at a solution
    a
    J=Favg*t
    200N/2*.01seconds=1kgm/s
    J=Δp=0-.25kg*4m/s= -1 kgm/s
    The impulse should be positive since its asking for the impulse on the wall and not the snow ball correct? I should have had
    .25kg*4m/s-0= 1 kgm/s ?
    b,
    Since the graph is of isosceles triangles I can just divide the max F by 2 to get 200N/2=100N
    Or use:
    Favg=m*v/t
    =(.250kg*4m/s)/.01s
    =100 N
    c.
    should just be the maximum force divided by the time interval between the peak of two impacts?
    200N/.05s
    4000N/s?
     
  2. jcsd
  3. Nov 16, 2016 #2
    For c:
    Favg=m*v/t?
    =(.250kg*4m/s)/.05s
    20N
     
  4. Nov 16, 2016 #3

    haruspex

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member
    2016 Award

    Apart from the mass of a snowball, you did not state any input numbers. I deduce you were told the impact velocity, the impact duration, the impact separation, and, redundantly, the peak force. As far as I can tell, your working is all correct.
     
  5. Nov 16, 2016 #4
    I should have looked at how the copy/paste had actually performed when posting the problem
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Impulse with snowballs hitting a wall
  1. Ball Hits Wall (Replies: 1)

  2. Car hits wall momentum (Replies: 3)

Loading...