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    U Physics 12E 7.71 Conservation of Energy: An experimental apparatus with mass

    o.k. i get it now. we are propagating a to limit the forces so the block/animal launched doesn't break/die. so that's why we pull out x from kx^2=ma then plug x into Uel=Ug. the objective again it to limit. then after we get the final equation, we can pick a k and an x-compression that will work.
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    U Physics 12E 7.71 Conservation of Energy: An experimental apparatus with mass

    The question is shown below the --- or this question and answerbook is from U Physics 12E #7.71. I uploaded a JPG that can be seen at http://i43.tinypic.com/35j9jja.jpg I don't understand this problem. I see that to solve this Conservation of Energy and N2L are merged using x, and that h from...
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    Stuck on algebra to N2L solution

    thanks. i wouldn't have figured that out by myself in a millions years ;-). i get the logic, solve 1 & 3 for a, then take a and plug back into 1.
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    Stuck on algebra to N2L solution

    please view these images here's the problem http://i54.tinypic.com/23h6slh.jpg the solution http://i56.tinypic.com/2hhok79.jpg
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    Stuck on algebra to N2L solution

    oh ! now i see. it's checking if the block on top is sliding on the slab. not deriving it.
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    Stuck on algebra to N2L solution

    o.k., i typed it here, but it's cryptic with (subscripts) these four N2L equations: -f = m(s) a(s) F(ns) -F(Nb) -m(s)g = 0 f - F = m(b) a(b) F(Nb) - m(b) g are shown in the soln to resolve to f = ( m(s) F ) / ( (m(s) + m(b) ) where do i begin ?
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    Stuck on algebra to N2L solution

    I already understand the problem, but am having trouble with the algebra for textbook Fund of Physics Solutions, Halliday, 8e, Ch6 Prob 34. Copied here http://i56.tinypic.com/20uwhw4.jpg I've been staring at this solution to N2L for hours and can't figure out how to go from the top 4 N2L...
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    Please help projectile motion question

    Yf=Yo+Voy-.5gt^2 =1.5+0-4.9t^2 1.5/4.9=t^2 t=0.553 seconds ....
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    Skydiver #1 #2 fall problem, Linear or Quadratic ?

    O.K. I got it now, thanks for your help ;-) ------------------------------------------------------- Yf= Yo + VoyT - .5gT^2 0 = 5280 - 12(427 - T) - 16T^2 = 5280 - 5124 + 12T - 16T^2 = -156 + 12T - 16T^2 the roots are -2.77, +3.51, and 3.51 is the RIGHT answer...
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    Skydiver #1 #2 fall problem, Linear or Quadratic ?

    i manually figured out that for Sky#2 to fall 5280 ft, it takes T = 3.5 secs 5280 = 12(427 - T) + (16 * T^2) next i tried with variable T 5280 = 12(427 - T) - 16T^2) 5280 = 5124 - 12T -16T^2 = -156 -12T -16T^2 the root is -.375, and it's wrong but if i manually change it...
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    Skydiver #1 #2 fall problem, Linear or Quadratic ?

    Next, I need to find T for Sky2 first, then I can calculate the free fall & chute-open times.
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    Skydiver #1 #2 fall problem, Linear or Quadratic ?

    from 0-2 sec (.5 x 32 x 2^2)= 64 ft 5280 ft - 64 ft = 5216 ft 5216 ft / 12 ft/s = 435 sec so sky1 takes 435 + 2 = 437 secs to hit ground sky2 jumps 10 secs later 437 - 10 = 427 secs 5280 = 0 + ( 12 x (427 - T)) + (.5 x 32 T^2) the last quadratic didn't work. hmm...
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    Skydiver #1 #2 fall problem, Linear or Quadratic ?

    Homework Statement Skydiver #1 from the University Skydiving Club steps out of a plane when it is 1 miles above the ground and 10 seconds later skydiver #2 steps out of a plane (at the same height). They both want to land on the ground at the same time. To make an estimate assume that...
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