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Can we define force if

  1. Feb 13, 2012 #1
    Can we define force if ......

    1. The problem statement, all variables and given/known data
    Can we define force if a body from high of ##h_1=4m## goes down to ##h_2=−3m##, for time ##t=4s##, and with velocity of ##v=10\frac{m}{s}##. The acceleration would be ##a=\frac{v}{t}=\frac{10\frac{m}{s}}{4s}=2.5 \frac{m}{s^2}.## Can we define the force using these things? If yes, let me know the formula, if no, let me know :)


    2. Relevant equations
    none


    3. The attempt at a solution
    none.
     
    Last edited: Feb 13, 2012
  2. jcsd
  3. Feb 13, 2012 #2

    wukunlin

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    Gold Member

    Re: Can we define force if ......

    F = ma, you need the mass as well as acceleration to find the force
     
  4. Feb 13, 2012 #3
    Re: Can we define force if ......

    I know ##F=ma##, but, I have the acceleration, but I don't want mass, I want to know if there's a way to find the Force with distance between two highs , with a velocity for a set time.
     
  5. Feb 13, 2012 #4

    Doc Al

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    Staff: Mentor

    Re: Can we define force if ......

    This kinematic data doesn't seem consistent. Did you just make it up?
    No.
     
  6. Feb 13, 2012 #5
    Re: Can we define force if ......

    Yeah, I made it my self, And I see you can't because ##m ,m , s, \frac{m}{s}## wouldn't be able to make ##N## (Newton) or ##kg\frac{m}{s^2}## which is ##kg\frac{m}{s^2}=N##
     
  7. Feb 14, 2012 #6
    Re: Can we define force if ......

    Way too many errors in it.
    Firstly you say that object goes from
    h1=4m goes down to h2=−3m ?

    How can you say that distance will be -3m ???? Distance is scalar !
    Secondly , yes we can define displacement to be negative with reference to direction but here body is falling uni-directionally. You have to say that body is falling from distance of 4m to 3m.

    Again another error : If body is falling downwards then acceleration will be 9.8 or 10m/s2 i.e constant value. This further implies that the velocity of body will keep on increasing by 9.8 or 10m/s , every second. You just can't say that velocity of body will be uniform here in this case.

    Again acceleration is rate of change in velocity , not velocity by time.
    And lastly , out of curiosity : Are you assuming another planet where acceleration is 2.5m/s2 ?:biggrin:

    You CANNOT define FORCE without using or taking MASS of object in ACCOUNT.
     
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