Density and measurement
- 1. Al Salam School Secondary Science Department Unit 1 :- Measurement in Physics Learning Objectives By the end of this section, you will be able to do the following: • Associate physical quantities with their International System of Units (SI) and perform conversions among SI units using scientific notation. • Relate measurement to significant figures and apply the rules of arithmetic’s for using significant figures in calculations. • Using various appropriate scales to find appropriate physical quantities. • Calculating unknown densities using the measurement of volume and mass using appropriate scales. 1.1 : Measuring units The measurements of physical quantities are expressed in terms of units, which are standardized values. For example, the length of a race, which is a physical quantity, can be expressed in meters (for sprinters) or kilometers (for long distance runners). All physical quantities in the International System of Units (SI) are expressed in terms of combinations of seven fundamental physical units, which are units for: length, mass, time, electric current, temperature, amount of a substance, and luminous intensity. SI units (acronym for the French Le Système International d’Unités, also known as the metric system or international system of units)
- 2. Al Salam School Secondary Science Department 2 In measurements, when dealing with very large or very small quantities, we need to add ‘prefixes. These are symbols that are used to make the number smaller and thus more manageable to use in further calculations. Here are some of the most common type of prefixes: Example of using prefixes
- 3. Al Salam School Secondary Science Department 3 Measuring Length: Tool used : Ruler
- 4. Al Salam School Secondary Science Department 4 Measuring Time:
- 5. Al Salam School Secondary Science Department 5 Measuring Mass:
- 6. Al Salam School Secondary Science Department 6 Measuring Volume: Solid For a regular shaped object, we can find the volume by multiplying its length, width and height as shown in the example below. For an irregular shaped object, the volume is measured using the water displacement method in a measuring cylinder.
- 7. Al Salam School Secondary Science Department 7 Liquid For liquids, we use graduated measuring cylinder, where we pour the liquid and read the meniscus of the level of the liquid.
- 8. Al Salam School Secondary Science Department 8 Finding Density
- 9. Al Salam School Secondary Science Department 9
- 10. Al Salam School Secondary Science Department 10 Density Lab Investigation In our Lab session, we investigated how the density of an irregularly shaped object can be found. A simple example is shown below to reiterate what was done in the lab.