# Math Help - Mass and Dimensions

1. ## Mass and Dimensions

Hello All...

This is my first posting so I am not sure if this is the right section.

I am having a hard time figuring out how to do this problem:

Question: Determine the mass of a tombstone made of the same material as the granite rock and having the dimensions of 260 cm by 90 by 40 cm. What is the mass of the tombstone?

..

I have not been given the mass of the granite rock yet, but once I do how would I set up this problem?

2. ## Re: Mass and Dimensions

Originally Posted by dempsey1905
Hello All...

This is my first posting so I am not sure if this is the right section.

I am having a hard time figuring out how to do this problem:

Question: Determine the mass of a tombstone made of the same material as the granite rock and having the dimensions of 260 cm by 90 by 40 cm. What is the mass of the tombstone?

..

I have not been given the mass of the granite rock yet, but once I do how would I set up this problem?
1. Use the definition of density of a material:

$density = \frac{mass}{volume}$ ....... Then $mass = density \cdot volume$

2. Have a look here: Granite - Wikipedia, the free encyclopedia

In this text about the various forms of granite you'll find: "The average density of granite is between 2.65 and 2.75 g/cm3, ...."

If I were you I would take $d_{granite} = 2.7\ \tfrac{g}{cm^3}$

3. Since you now know the mass of 1 cm³ of granite you only have to determine the volume of the tombstone. Go ahead!

Thank you!