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Homework Help: Forces (Newton's Law) Help

  1. Oct 1, 2006 #1
    A shopper in a supermarket pushes a loaded cart with a horizontal force of 13 N. The cart has a mass of 33 kg.

    (a) How far will it move in 3.0 s, starting from rest? (Ignore friction.) M

    (b) How far will it move in 3.0 s if the shopper places his 30 N child in the cart before he begins to push it? M

    I figure out A but stuck on B and have no clue what to do after getting it incorrect 3 times.

    for A I did F = ma a = .39 then I used V = at to get V = 1.17
    then i used V^2 - V_0^2 = 2aDeltaX to get DeltaX = 1.76m

    I tried using something like that for b but incorrect.

    I tried finding a_x and a_y but it gave me an incorrect answer. Any pointer would be very helpful. Thanks in advance
  2. jcsd
  3. Oct 1, 2006 #2
    The weight of the child is 30N, so what is the child's mass?

    Btw, for the first, you could have as well used s = 0.5at^2
  4. Oct 1, 2006 #3
    i think the trick here is tt they gave you mass of cart and weight of baby.....so jus find either mass of baby or weight of cart then sum them up and treat them as a big object. After that i think you can get distance using EOM.
  5. Oct 1, 2006 #4
    Thanks a lot that really helped out.
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