Calculating distance using spring constant, mass and velocity? (Really basic stuff )

  1. Calculating distance using spring constant, mass and velocity? (Really basic stuff!!)

    Hi I have a physics exam tomorrow, and I just realized we haven't covered either impulse or spring constants, and about 1 1/2 hours left to study. From a practice exam, please someone help me out?

    1. The problem statement, all variables and given/known data

    A high impact crash helmet is glued onto a floor and a 5.0kg steel ball is dropped from a certain height in the helmet padding. The ball hits the helmet padding at 0.85m/s. The spring constant of the padding amterial is 35kN/m.

    2. Relevant equations

    distance = Force/spring constant(k)
    Most likely an impulse on as well

    3. The attempt at a solution

    d=F/k
    impulse = mv = 5 x 0.85 = 4.25
    d = 4.25 / 35000 = 1.2 x 10^-4

    This one is not so important:
    Also, in a previous question, they gave a linear graph, at one point, N = 300 and displacement = 0.06 metres. Find the spring constant?

    I got
    k = f/d = 300/0.06 = 5000 N/m

    Is this right? (Couldn't find the answer's to the practice exam)

    Also, any tips on learning these in about 20 minutes? Thanks, and sorry for massive post.
     
  2. jcsd
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