Measurement of Length
Ensure to keep your ruler straight along the length of an object.
Point A is the start point zero of the ruler and point B is the end point for measuring length.
The reading of the ruler at point B gives the length of an object. Here the point B reads as 13 cm, that is the length of an object measured is 13 cm.
Precautions we should take while measuring length.
(1) Keep the ruler straight along the length of an object to be measured or else we will not get the correct measurement.
( show by diagram)
If we tilt the ruler, the ruler does not give correct measurement.
2. In some scales, the ends of the ruler may be broken. You may not be able to see the zero mark clearly.
In such cases, you should avoid taking measurements from the zero mark of the scale.
You can use any other full mark of the scale, say, 1.0 cm
Then you must subtract the reading of this mark from the reading at the other end. For example the reading at one end is 1.0 cm and at the other end it is 14.3 cm.
Therefore, the length of the object is (14.3-1.0) cm = 13.3 cm.
3. Keep your eye vertically above the point where measurement is to be taken.
The readings from different positions would be different.
The correct position is just vertically above the reading of the scale to be noted.
Using measuring tape to measure height of a boy
Remove the shoes of a boy and make him stand straight with back against the wall.
Make sure legs are straight, arms are at sides, and shoulders are level.
Place a scale on his head and make a mark on the wall
Measure the length from mark to the floor with a measuring tape
Take all precautions for correct measurement of length.
Record the height of a boy with the help of an inch tape.
MEASURING THE LENGTH OF A CURVED LINE
We cannot measure the length of a curved line directly by using a meter scale. We can use a thread to measure the length of a curved line.
(1) Use a thread to measure the length of the curved line AB.
(2) Put a knot on the thread near one of its ends.
(3) Place this knot on the point A. Now, place a thread along the line using your fingers and thumb.
(4) Make a mark on the thread where it touches the end B. Now stretch the thread along a meter scale
(5) Measure the length of the thread from the beginning and the final mark. This gives the length of the curved line AB.
We need to ensure to take a lot of care to ensure that we are measuring distances and lengths correctly.
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