What is the weight of a 1500 kg car on Planet X?

[cmNickoli7]

Homework Statement

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?

Homework Equations

some Formulas I used in solving this:

W = m*g

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

 

[SammyS]

Homework Statement

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?

Homework Equations

some Formulas I used in solving this:

W = m*g

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

Your result looks right.

Try a negative answer.

 

[ap123]

If you look at the source code for the web page, it actually displays the answers

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.)