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Homework Help: Spring scales and forces!

  1. Jul 12, 2004 #1
    im having problems with this particular question...

    the problem asks:

    Two forces are applied to the cart with two different spring scales as shown below. The spring scale F1 reads 2.0 N. The cart moves toward the right with an acceleration toward the right of 1.50 m/s/s.

    (a) What is the net force acting on the cart? (show calculations)

    (b) What does spring scale F2 read? (show calculations)

    ...brain teaser huh? :frown:

    thanx for help guys
  2. jcsd
  3. Jul 12, 2004 #2


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    You should know a formula:

    [tex]F_{net} = ma[/tex]

    For the first question, you know the acceleration and should know the mass, so you can calculate the net force. For the second question, you know that the net force is comprised of two forces acting in opposite directions. Knowing the net force and one of the applied forces, you can calculate the other applied force.
  4. Jul 13, 2004 #3
    keyword u said : SHOULD know the mass...but we dont! :mad:

    so i sat thinking about it for about 20 mins...and my conclusion was this:

    is it possible to use F = M x A to find out the mass first...then use the same equation to find the net force?

    what i did was as follows: F = M x A
    2.0 (n) = M x 1.50 (m/s/s)
    M = 0.75 (Kg)

    Once i found the mass...i said F<net> = M x A
    F<net> = 0.75 (kg) x 1.5 (m/s/s)
    F<net> = 1.125 N

    then for F2 i did simple subtraction F2 - F<net> = F1
    2.0 - 1.125 = 0.875 N

    Does any of this i did make sense? or is it correct? either way i cant change it because im turning in my homework in about an hour :frown:
    But please give me your guys' input. Thanks alot! :approve:
    Last edited: Jul 13, 2004
  5. Jul 13, 2004 #4
    If you know the NET force, why even bother?

    This doesn't make any sense because your suggesting that F1 is the only force acting on the cart, which is not true.

    No and NO. You said the mass of the cart is an unknown so I think you can't solve this problem. There seems to be some sort of pictorial representation of this problem (judging by your wording in the first post). Can you scan that and post it here for further examination.
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