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Homework Help: Ap physics questions on basic kinetics and newtons second law

  1. Apr 10, 2012 #1
    1)A rock is dropped off a cliff and falls the first half of the distance in to the ground in t1 seconds. If it falls the second half of the distance in t2 seconds, what is the value of t2/t1?

    Relevant equations: I think the kinematics equations of d=vt+(1/2)at^2
    I have no idea how to solve this please help!! I tried to find t1 with the equation above and god t1=sq.rt(d/5) but i don't know if this is right :)

    2)a bos of mass m slides on a horizontal surface with initial speed v. I feels no forces other than gravity and the force from the surface. If the coefficient of kinetic friction between the box and the surface is mu how far does the box slide before coming to rest?
    Relevant equations: f=ma Ff=Fn*mu,
    I basically drew a free body diagram so far
  2. jcsd
  3. Apr 11, 2012 #2
    isnt this an introductory physics question
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