Gravity and Mass Homework: 0.000000364kg

[woaini]

Homework Statement

A 3.0 kg spherical flask is placed on a scale and balanced. Then a ball with a mass of 5775 kg is placed directly underneath the flask, resulting in a center-to-center distance of 56.9 cm. How much mass would have to be added to the other side of the scale in order to re-balance it?

G = 6.67 x 10^-11 Nm^2/kg^2
m1=3kg
m2=5775kg
r=0.569m

Homework Equations

(G*m1*m2)/r^2 = mg

The Attempt at a Solution

m=$\frac{G*m1*m2}{r^2*g}$

m=$\frac{(6.67*10^-11)*(3)*(5775)}{(.569)^2*(9.81)}$

m=0.000000364 kg

 

[nasu]

Do you have a question?

 

[woaini]

Do you have a question?

Did I setup the equation right?

 

[nasu]

It looks OK to me.

 

[Nickie]

The mass of 0.000000364 kg is very small and may be due to rounding errors. It is possible that the scale may not be sensitive enough to accurately measure such a small amount of mass. Alternatively, it is also possible that the calculation may have been done incorrectly. If the scale is able to measure such small masses, then adding this amount to the other side of the scale would re-balance it. However, if the scale is not sensitive enough, a larger mass would need to be added to re-balance it. This exercise shows the importance of considering both gravity and mass in determining the balance of a scale.