# Measurement

### Measuring Instruments

#### MEASURING MASS

###### BALANCE

Example:

The mass of the salt cube is 500 g + 200 g + 50 g = 750 g

###### TRIPLE BEAM BALANCE

Example:

The mass of the object is 300 g + 60 g + 6.5 g = 366.5 g

#### MEASURING LENGTH

###### Example:

The length of the rod is 3.3 cm – 1.1 cm = 2.2 cm

###### Example:

Main Scale = 1.2 cm

Vernier Scale = 7 × 0.01 cm = 0.07 cm

Reading = 1.2 cm + 0.07 cm = 1.27 cm

###### Example:

Main Scale = 4.0 mm

Thimble Scale = 25 × 0.01 mm = 0.25 mm

Reading = 4.0 mm + 0.25 mm = 4.25 mm

#### MEASURING VOLUME OF LIQUID AND IRREGULAR OBJECT

In narrow glass cylinder, the liquid level is curved into a shape called the meniscus.

For most liquids such as water, the meniscus curves as shown in figure below.

To get correct reading, make sure your eyes are the same level as the bottom of the meniscus to avoid parallax error.

###### MEASURING CYLINDER

1. Observe and note down the amount of water in the measuring cylinder (V1)
2. Tie the object with a piece of string and lower it slowly until it is completely submerged. Note the new water level (V2)
3. Find the volume of the object by subtract the new water level with initial water level (V2 - V1)

Measurement: 43 mL – 19 mL = 24 mL

###### DISPLACEMENT CAN

1. Fill a displacement can with water to the level spout. Allow excess water to flow into a container. When the water stops flowing, replace the container with an empty and dry measuring cylinder
2. Tie a piece of string to the object and lower it into the displacement can till it is completely submerged. Some water is displaced into the measuring cylinder. Note the volume of water displaced by the object

#### MEASURING TIME

###### ANALOGUE STOPWATCH

Reading time = 10 min  17 sec  = (10 × 60 sec) + 17 sec = 617 sec