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To investigate experimentally the relationship between the mass and volume of liquids and regular solids, and analyse and interpret the data gathered.

The main variables in a science experiment are the independent variable, the dependent variable and the control variables.

The Independent Variable is what we change or control in the experiment.

The Dependent Variable is what we are testing and will be measured in the experiment.

The Control Variables are what we keep the same during the experiment to make sure it’s a fair test.

Variables

In this experiment the:

• Independent Variable is the volume of the object.
• Dependent Variable is the mass of the object.
• Control Variables are the material of the object, room temperature, and temperature of the water.

Remember - these variables are controlled (or kept the same) because to make it a fair test, only 1 variable can be changed, which in this case is the volume of the object.

Equation

Prediction

As the volume of the material increases, the mass will also increase.

Justification for the prediction

The greater the volume of the object the greater the number of atoms present.

This will result in the object having greater mass.

Regular objects

Apparatus

Six regular objects of the same material but different volumes, a half-metre rule, a top pan balance.

Method

1. Select the smallest object. Measure the length, breadth and height using a half-metre rule. Record the results in cm in a suitable table.
2. Repeat each of these measurements of length, breadth and height and calculate the average.
3. Using the average values of length, breadth and height, calculate the volume of the object using: Volume = length x breadth x height. Record the volume in cm³ in the table.
4. Place the object on the top pan balance. Record the mass in g in the table.
5. Repeat the procedure for the other five objects.

Results

Graph

Plot a graph of mass in g on the y-axis against volume in cm³ on the x-axis.

Draw a line of best fit through the points.

Calculate the gradient of the graph and hence the density of the object.

Conclusion

We can see from the graph that as the volume of the object increases its mass also increases.

This agrees with our prediction.

In fact, since the line of best fit is a straight line through the origin, we can be even more precise.

We can say that the volume of the object is directly proportional to its mass.

As the volume increases the mass of the object increases in direct proportion.

The gradient of the graph equals the density of the material.

Cause of error

The main cause of error in this experiment is the measurement of length, breadth and height.

This can be kept to a minimum by repeating each measurement and calculating the average.