Question

MEDAL GIVEN TO CORRECT ANSWER.
A 2 kg laptop sits on the floor near a 4 kg jar of pennies. If the force of gravity between them is 3.42 10-10 N, how far apart are they?

A. 2.1 m
B. 1.6 m
C. 1.2 m
D. 1.8 m

Answer 1

For reference, you can still look at http://openstudy.com/study#/updates/52c77b0fe4b0095f1003fd66

So, you're looking at the force of gravity. And it looks like you want the Universal Law of Gravitation. It's a relationship that can be written as an equation.

Do you know what that equation is?

Answer 2

is the equation still F=G=m1*m2/r2?

Answer 3

F=G\(\large\text *\)m1*m2/r\(\large\text ^\)2

Answer 4

Do you see the differences? And that is the equation :)

Answer 5

so what number would be r^2?
i have it up to there i think.
so far it's 3.42*2*4/? @theEric

Answer 6

F=G*m1*m2/ r^2
F=3.42*10^-10
G=6.672*10^-11
m1=2
m2=4
r=?? unknown ??

Answer 7

I should've spaced that out better... The equation is at the top, and the given values are below it.

Answer 8

G=6.674*10^-11, sorry!

Answer 9

so if r is unknown, that must be what im trying to find.
So wouldnt the equation be switched around to where it says r=then the equation? @theEric

Answer 10

Yep!! :) Now you're getting there! :)

Answer 11

Give it a shot!

Answer 12

I honestly have no idea.
would you just switch r & f?
so it's r=g*m1*m2/f?

Answer 13

@theEric

Answer 14

Yes you would!!!

Now you can use a calculator, and substitute in the values I listed above!

Answer 15

Well wait...

Answer 16

that is r^2! r squared! \(r^2\)

So make sure you see that. You can take the square root of both sides to finish solving for r!

Answer 17

Then substitute.

Answer 18

i got 15.6
what did i do wrong? -.- @theEric

Answer 19

Two things! One, you didn't remember to use the times 10^-11 and 10^-10. Two, you didn't take the square root of it all.

Don't worry, you're getting there!

Answer 20

I got 1.2
is that correct? @theeric

Answer 21

Final answer?


I agree.

Congratulations! :)