laboratory equipment metric ruler. many laboratory activities require measurements. science uses the...

LABORATORY EQUIPMENTMETRIC RULER

Many laboratory activities require measurements.

Science uses the S.I. (Metric System) of measurements.

Types of measurements:

–Linear (length or distance)

–Mass (weight)

–Volume

–Temperature

All measuring instruments have calibrations. These are the markings or divisions on the measuring tool.

Linear measurements are made using a Meter Stick or Metric Ruler.

Metric Ruler

Meter Stick

The basic unit for linear measurement is the meter (m.). Other commonly used units are the centimeter (cm.) and millimeter (mm.).One advantage of the metric system is that everything is based on the number, 10, or some multiple of 10.

10 mm. = 1 cm. (and 1 mm. = 0.1 cm.)

100 cm. = 1 m. (and 1 cm. = 0.01 m.)

Also, 1000 m. = 1 kilogram (kg.).

A metric ruler

cm. marks mm. marks

Lets find this point!

Metric DetailsMillimeters and Centimeters

10 millimeters = 1 Centimeter10 millimeters = 1 Centimeter10 Centimeters = 1 Decimeter10 Centimeters = 1 Decimeter

1 2

2 centimeters

Metric DetailsMillimeters and Centimeters

10 millimeters = 1 Centimeter10 millimeters = 1 Centimeter10 Centimeters = 1 Decimeter10 Centimeters = 1 Decimeter

10 Centimeters or 1 Decimeter

Lets find this point!

1

When making measurements, scientists use a concept and a practice known as significant

figures (Sig. Figs.)

Significant figures include an estimated digit that is always one place beyond the calibrations on any measuring instrument.

Estimating the last digit in a measurement

You might estimate the end of the cylinder to be half-way between the lines or 0.05 cm. This digit must be included in the measurement.

Estimating the last digit in a measurement

This measurement should be read as 4.95 cm. This measurement has 3 significant figures.

Reading a metric ruler correctly:

This point can be read as 1.65 cm. or 16.5 mm.

Reading a metric ruler correctly:

This point can be read as 6.70 cm. or 67.0 mm.

Mass measurements are made using a balance.

There are several kinds of balances:

• Triple beam balance

• Dial-a-gram balance

• Electronic/ digital balance

• Analytical balance

The triple beam balance:

Mass, in the metric system, is measured in grams (g.), centigrams (cg.) or milligrams

(mg.).

10 mg. = 1 cg. (and 1 mg. = 0.1 cg.)

100 cg. = 1 g. (and 1 cg. = 0.01 g.)

Also, 1000 g. = 1 kilogram (kg.)

As with all measuring instruments, Sig. Fig. Rules must be followed when reading a balance.

How would you read this measurement?How would you read this measurement?

This should be read as 105.00 grams (g.)This should be read as 105.00 grams (g.)

How would you read this measurement?