An object has a weight of 9 N when it is in the air and 7.2 N when it is submerged into water. What is the specific gravity of the object’s material? Help! How do I solve without having a volume?

Answer 1

Hi Kate!

I have given a full explanation in the video above, but the core of the answer revolves around the definition of specific gravity-- it is the ratio of the density of the object to the density of water. Since density is essentially a

'rate' of sorts, the amount of mass per unit volume (here kg/m^3), we can take our equations for the weight of the object in air and the weight of the object in water and restate them in terms of densities. Then, we can solve for the density of the object by solving this system of equations. Finally, we divide the density of our object by the density of water. I give a full walkthrough of the setup and equations in the video, for more details. I hope this helps!

Best,

Jade