1.6 - Learning How to Use Measuring Tools

1.6 - Learning How to Use Measuring Tools

Measuring length.


The S.I. unit for length is metre ( m ) . The short lengths : centimetres ( cm ) or milimetres ( mm ) . Long distances : kilometres ( km ) .

Tools for measuring length . 


The metre rule , half-metre rule or ruler .
To measure the length of short straight lines . 
The correct eye position is very important in order to obtain an accurate reading . The error caused by an incorrect eye position when taking a measurements known as parallax error .

The measuring tape .
 
To measure the length of straight lines . 

Thread and metre rule. 

We can use thread , together with a metre rule , to measure the length of a curved line .

 

And

 

External and internal calipers .


We can use calipers , together with a metre rule , to measure the diameters of round or cylindrical objects , External calipers : To measure the external diameter of an object . Internal calipers : To measure the internal diameter of an object .

External calipers .

Internal Calipers

Measuring area .

We can estimate the area of regular or irregular shapes by tracing the shapes onto a piece of graph paper . The methods are :
Count the number of complete squares .
An incomplete square is counted if half or more of the square is covered .
Do not count an incomplete square if less than half of the square is covered .

Measuring volume.

Measuring cylinder , burette , pipette are used for measure the volume of a liquid . 
We usually measure the volume of a liquid in milimetres ( ml ) and the volume of a solid in cubic centimetres .

Measuring Cylinder .

Burette .

Pipette .

Finding the volume of a regular object and an irregular object using the water displacement method . 

The volume of a regular object and an irregular object can be measured by using the water diplacement method . 
In this method , the object is dropped into a measuring cylinder filled with water . This will cause the water level in the measuring cylinder to rise . The water level rises because the water in the mesuring cylinder has been diplaced by the object .
The increase in the volume of water in the measuring cylinder is equal to the volume of the object .