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## Measuring Length For curved lines, use a thread to measure the length. Mark the thread at either end of the line and then lay it along a ruler. ## Measuring Volumes There are two approaches to measuring volumes, depending on whether or not the shape is regular. ### Regular Shapes * **Cube or...

## Measuring Length For curved lines, use a thread to measure the length. Mark the thread at either end of the line and then lay it along a ruler. ## Measuring Volumes There are two approaches to measuring volumes, depending on whether or not the shape is regular. ### Regular Shapes * **Cube or cuboid:** Measure the length, width and height of the object and multiply the measurements together. ### Irregular Shapes * **Measuring volume by displacement:** * Select a measuring cylinder that is about three or four times larger than the object. * Partially fill it with water and note the volume of the water. * Immerse the object in the water. * The increase in the volume of the water is equal to the volume of the object. ## Units * **SI units:** The SI unit of length is the metre (m). * **Volume:** * One litre (1 l) is the same as 1 dm³. * One millilitre (1 ml) is the same as 1 cm³. ## Key words * **Volume:** The space occupied by an object. * **Meniscus:** Curved upper surface of a liquid. * **Displace:** Moving something to another place so water is moved out of the way (upwards) when an object is lowered into it. * **Immerse:** To cover something in a fluid (usually water) so that the object is submerged. ## Measuring Liquid Volumes * Look at the scale horizontally, not at an oblique angle, and read the level of the bottom of the *meniscus*. * A 1 litre (or a 1 dm³) cylinder is unlikely to be suitable for measuring a small volume such as 5 cm³. You will get a more accurate answer using a 10 cm³ cylinder. ### Figure 1.7: Measuring volume by displacement | Quantity | Unit | |---------|-----| | length | metre (m) | | volume | cubic metre (m³) | ### Figure 1.8: Measuring the volume of a block of steel: * The student is using a measuring cylinder to measure the volume of the steel block. * The block of steel is submerged in the water.