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Homework Help: Need Work Checked please

  1. May 7, 2013 #1
    1. The problem statement, all variables and given/known data

    On Planet X, a 70 kg object can be lifted by a force of 400 N.

    a. What is the acceleration of gravity on Planet X?

    c. Suppose your car was taken to Planet X. If the car has a mass of 1500 kg, what would its weight be?

    2. Relevant equations

    some Formulas I used in solving this:

    W = m*g

    3. The attempt at a solution

    A: W = m*g

    400 = 70*g

    400/70 = g

    g ≈ 5.7 m/s^2

    *I checked this and I know that it was correct. So, I used this in the second part of the question as my "g" *

    C: W = m*g

    W = 1500*5.7

    W = 8550 N

    *On the website, I put this in the form field and it said it was wrong, So, I got more specific.*

    W = 1500*(400/70)

    W ≈ 8571.4258571

    W ≈ 8571.4 N

    *still told me I was wrong. So i tried variations of Significant Digits (8571.43, 8571.426, 8571) all of which, the website said i was wrong. I really would like it if someone could check to make sure that I calculated it right, or if I did something wrong.*

    I am teaching myself physics from this website and I am doing well. Although, it is telling me I am wrong, I am not so sure. Of course it could be an error in my calculations but I would like the help of a second pair of eyes. Thanks for taking the time to read this.

    The Website Link is : http://library.thinkquest.org/10796/ch4/ch4q.htm
  2. jcsd
  3. May 7, 2013 #2


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    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    Your result looks right.

    Try a negative answer.
  4. May 8, 2013 #3
    If you look at the source code for the web page, it actually displays the answers :smile:

    The answer given is 8565N. Working back, it therefore wants you to use g = 5.71m/s2

    (The number of significant figures used for the problems on this page are a bit messed up.)
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