Measuring the Physical World What you may already know:
z z
Some quantities can be measured, such as time, length, area, volume and speed.
To measure things we use instruments, such as a stopwatch, a ruler, a measuring jug or even a Garda speed gun.
What you will learn in this chapter:
z SI units are the standard units of measurement in most countries.
z The difference between basic and derived units.
z Physical quantities that we can measure and the ways we can measure them.
z The difference between random errors and systematic errors when taking measurements.
z z Can you crack this code? 1. 2. 3.
Orange Green
Yellow Blue Violet
? Red 4.
Why do we measure and have units?
Why are there 24 hours in a day?
The first letter of each image spells out a key word you will come across in this chapter. Use the hints provided if you need to, or revisit the Puzzler after you finish this chapter.
