A student finds a rock that has a mass of 74.00 grams. When he places the rock into a graduated cylinder with 50.00 mL of water, the water level goes up 86.40mL. What is the volume of the rock?...

A student finds a rock that has a mass of 74.00 grams. When he places the rock into a graduated cylinder with 50.00 mL of water, the water level goes up 86.40mL. What is the volume of the rock? What is the density of the rock?

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gsenviro's profile pic

gsenviro | College Teacher | (Level 1) Educator Emeritus

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The volume of the rock is the same as the amount of water it displaces, I.e. 86.4-50 ml = 36.4 ml.

Archimedes used the water displacement method to figure out the density of materials.

The density of an object is given as the ratio of mass to its volume.

Here, the mass of the given rock is 74 grams and its volume is 36.4 ml.

Thus the density is 74/36.4 gm/ml 

= 2.033 gm/ml.

Hope this helps.

Sources:
chasman's profile pic

chasman | Elementary School Teacher | eNotes Newbie

Posted on

A student finds a rock that has a mass of 74.00 grams. When he places the rock into a graduated cylinder with 50.00 mL of water, the water level goes up 86.40mL. What is the volume of the rock? What is the density of the rock?

First, write down the information you are given:

Given:  Mass, 74.00 g

           V1=50.00mL

           V2=86.40 mL

Wanted:  Volume of Rock; Density of rock

Procedure:  The volume of rock is the difference in volume between the graduated cylinder with the rock in it (V2) and the initial volume of the rock (V1).  Volume of rock=V2-V1

          Volume of rock=86.40mL - 50 mL

          Volume of rock= 36.4 ML

The density of the rock is the mass of the rock divided by the volume of the rock. 

       Density of rock = mass/volume

       Density of rock = 74g/36.4mL = 2.03 g/mL

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Jessica | Middle School Teacher | eNotes Newbie

Posted on

The volume (V) of the rock equals the final volume of the graduated cylinder minus the initial volume of the graduated cylinder.

V = Vf - Vi

V = 86.40 mL - 50.00 mL = 36.40 mL (four significant figures)

The density (D) of the rock equals mass (M) of the rock divided by the volume (V) of the rock.

D = M/V

D = 74.00 g / 36.40 mL = 2.033 g/mL (four significant figures)

chemrock's profile pic

chemrock | College Teacher | eNotes Newbie

Posted on

A student finds a rock that has a mass of 74.00 grams. When he places the rock into a graduated cylinder with 50.00 mL of water, the water level goes up 86.40mL. What is the volume of the rock? What is the density of the rock?

mass of rock=74.0 grams

water level before adding rock=50.0mL

water level after adding rock=86.4mL

Volume occupied by rock=water level after adding rock-water level before adding rock

=86.4-50.0=36.4mL

Volume of rock=36.4mL

density of rock=mass of rock/volume of rock=74.0g/36.4mL=2.033g/mL

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