MEASUREMENT

To measure a physical quantity, we need some instruments; for example, the quantity of length can be measured by instruments such as a ruler, vernier caliper and micrometer screw gauge.

1.    Measurement of Length

To measure the quantity of length, we can use a ruler, vernier caliper or micrometer screw gauge. However, those instruments mentioned have their own strengths and weakness.

a.  Ruler

Ruler is an instrument to measure length which usually has smallest scale of 1 mm. But there are also rulers whose smallest scale is bigger than 1 mm, for example 1 cm. 

b.  Vernier Caliper

Vernier caliper is an instrument to measure length which is more accurate than a ruler, since it has the smallest scale of 0.1 mm.

c.   Micrometer Screw Gauge

A micrometer screw gauge is an instrument to measure length which is more accurate than a ruler or a vernier caliper, because it has smallest scale of 0.01 mm.

2.    Measurement of Mass

To measure the quantity of mass, we can use balances. There are several balances that are often used, such as cross-bean balance, spring balance, and digital balance.

3.    Measurement of Time

Life time is between birth and death. The SI unit for time is second (s). One standard second is the time needed by Cesium atom to vibrate 9,192,631,770 times. Based on this atomic hour, during 300 years the result of measurement will not miss more than a second. For long events, time is stated in larger units such as minute, hour, day, month, year, century, etc.

1 day = 24 hours

1 hour = 60 minutes

1 minute = 60 seconds

But for a fast event, you can use millisecond (ms),microsecond (μs), and nanosecond (ns).

4.    Temperature

Temperature is one of the fundamental quantities. During the day we feel hot, but cool at night. Fire is hot, but ice is cold. A hot object is said to have high temperature, but a cold object has low temperature. Thus temperature shows the degree of hotness and coldness of an object. Your palm can feel the hotness or coldness of a thing.

The common measuring tool for temperature is a thermometer. A thermometer consists of a long glass tube with a narrow column, called capillary pipe, containing liquid, alcohol or mercury. But, the upper part is vacuum.

5.    Volume

Big and small bucket can contain different amount of water. The big bucket contains more water than the small one does. This is related to the space occupied by that object,called volume. The bigger volume takes more space than the small one.

Volume is a derived quantity, from the fundamental quantity of length. For regularly shaped object, you can measure the length, width, and height and multiply them. If you measure the length, width, and height of a rectangular block in cm, the volume is cubic centimeter (cm3).Likewise, if the unit is meter, the volume is cubic meter (m3).

How can you measure the volume of a liquid? The volume of a liquid may be measured by pouring it into a measuring cylinder. When the liquid is poured into the measuring cylinder, the space occupied by the liquid is its volume.