Investigating the densities of solids and liquids

In a nutshell

By measuring the properties of solids and liquids, you will investigate their densities. You will do this by conducting three different experiments. The first will measure the mass and volume of a regularly-shaped solids; the second will use the displacement technique to find the density of irregularly-shaped solids and the third will involve finding the mass and volume of liquids.

Equations

Word Equation	Symbol Equation
$density = \frac{mass}{volume}$	$\rho = \frac{m}V$

Variable definitions

Quantity Name	Symbol	Unit name	Unit
$density$	$\rho$	$kilogram \space per \space metre \space cube$	$kg/m^3$
$mass$	$m$	$kilogram$	$kg$
$volume$	$V$	$metre \space cube$	$m^3$

Equipment list

The following equipment list can be used to conduct the experiment to investigate the densities of solids and liquids.

Equipment	Use
Regular shaped solids	To find the density of. There should be a variety of sizes.
$30\,cm$ ruler	To measure the volume of the regularly shaped solids. This is good for larger objects.
Vernier calliper	To measure the volume of the regularly shaped solids. This is good for smaller objects.
Micrometer	To measure the volume of the regularly shaped solids. This is good for very small objects.
Digital balance	To measure the mass of the solids and liquids.
Irregularly shaped solids	To find the density of.
'Eureka' can (displacement can)	To measure the volume of the irregularly shaped solids. The solid will displace the same volume of water as its own volume.
A liquid (e.g. a salt or sugar solution)	To find the density of.
Measuring cylinder	To find the volume of the liquid.

Experiment 1: Investigating the densities of regular shaped solids

Experimental variables

The independent variable is the variable you change. The dependent variable is the variable that changes depending on the other variables, and is the one you measure. The control variables are the variables that are kept constant.

Independent Variable	$The\ solid$
Dependent Variable	$Mass,\ volume$
Control Variables	$Measuring\ equipment$

Safety precautions

When performing experiments, it is very important to consider safety precautions. This is so that no one gets hurt or injured during the experiment.

Hazard	Risk	Safety Measure
Vernier calliper	The points of the calliper may be sharp.	Take care when using the calliper. Place in their bag when not in use.

Method

These are the instructions to complete the experiment. Record all measurements taken as you work through the experiment in a table.

Physics; Physics practicals; KS4 Year 10; Investigating the densities of solids and liquids

1.	Vernier calliper
2.	Micrometer
3.	Regular shaped objects
4.	Digital balance
5.	Ruler

1.	Place the regular shaped solid on the digital balance and record its mass.
2.	Use the appropriate measuring device to record the dimensions of the object (width, height, depth, radius, etc.). Tip: Find the formulas for the volume calculations and check you have measured all of the variables.
3.	Repeat steps 1 and 2 twice more and find an average for each measurement.
4.	Repeat steps 1-3 for as many regularly shaped solids as you have. Make sure to change the variables measured depending on the shape of the object.

Analysis

This is how you will use the data recorded to form conclusions.

1.	Calculate the volume for each regular shaped solid. Make sure to use the average result of your dimensions measurements. Note: Remember to convert all measurements in $cm$ to $m$ !
2.	Calculate the density for each regularly shaped solid using the formula $density = \frac{mass}{volume}\newline \ \newline \rho = \frac{m}{V}$

Conclusion

The results of the experiment should show how mass, volume and density are related. The density of an object should tell you how much mass it has for every unit of volume.

Evaluation

Once you have completed your experiment, it is important to consider how it could be improved. You should come up with ways to improve the accuracy of your values. If you got a result that seems unreasonable, think about why this was.

Experiment 2: Investigating the densities of irregular shaped solids

Safety precautions

When performing experiments, it is very important to consider safety precautions. This is so that no one gets hurt or injured during the experiment.

Hazard	Risk	Safety Measure
Spilling water	Water spilt on the floor may create a slippery environment. This could lead to injury or damage to equipment.	Perform the rest of the experiment next to the sink if possible. Don't overfill the can.
Water and electrics	The digital balance could break or even cause a fire if water gets in the electrics.	Pour the water in the sink. Perform the rest of the experiment away from the digital balance.

Method

These are the instructions to complete the experiment. Record all measurements taken as you work through the experiment in a table.

Physics; Physics practicals; KS4 Year 10; Investigating the densities of solids and liquids

1.	Eureka can
2.	Measuring cylinder

1.	Place the irregularly shaped object on the digital balance and record the mass.
2.	Fill the eureka can with water up to a point below the spout.
3.	Place the measuring cylinder under the spout of the eureka can. This is where the displaced water will go.
4.	Lower the object into the eureka can. This should be done gently to avoid more water being displaced than there should be.
5.	Measure the volume of displaced water in the measuring cylinder.
6.	Repeat all previous steps twice more to get an average for all measurements.

Analysis

This is how you will use the data recorded to form conclusions.

1.	The volume of the water displaced is the same as the volume of the object. This will be given in $ml$ which can be converted to $m^3$ by dividing by $1\,000\,000$ .
2.	Calculate the density of the object using the formula for density.

Conclusion

This is the same as the previous experiment.

Evaluation

This is the same as the previous experiment.

Experiment 3: Investigating the densities of liquids

Safety precautions

When performing experiments, it is very important to consider safety precautions. This is so that no one gets hurt or injured during the experiment.

Hazard	Risk	Safety measure
Spilling water	Water spilt on the floor may create a slippery environment. This could lead to injury or damage to equipment.	Perform the rest of the experiment next to the sink if possible. Don't overfill the can.
Water and electrics	The digital balance could break or even cause a fire if water gets in the electrics.	Pour the water in the sink. Perform the rest of the experiment away from the digital balance.

Method

These are the instructions to complete the experiment. Record all measurements taken as you work through the experiment in a table.

Physics; Physics practicals; KS4 Year 10; Investigating the densities of solids and liquids

1.	Measuring cylinder
2.	Liquid solution
3.	Digital balance

1.	Place the measuring cylinder on the digital balance and record the mass.
2.	Fill the cylinder with the liquid and record the volume that it fills.
3.	Record the new reading on the digital balance.
4.	Repeat steps 2-3 twice more and find an average for each set of measurements.

Analysis

This is how you will use the data recorded to form conclusions.

1.	Find the mass of the liquid by subtracting the average measurement of the initial reading of just the cylinder's mass from the final reading of the cylinder and the liquid's mass. $mass\space of\space liquid = mass \space of\space cylinder\space and\space water - mass\space of \space cylinder$
2.	Check the units of the mass ( $kg$ ) and volume ( $m^3$ ) are correct.
3.	Calculate the density using the density equation.

Conclusion

This is the same as the previous experiment.

Evaluation

This is the same as the previous experiment.