Advertisements
Advertisements
Question
Describe in steps how would you measure the length of a pencil using a metre rule. Draw a diagram if necessary.
Advertisements
Solution
To measure the length of a pencil using a metre rule, place metre rule with its marking close to the object. Let PQ be a pencil.
The end P of the pencil coincides with the zero marks on the ruler. The end Q of the pencil is read by keeping the eye at the position ‘B’ vertically above the end Q. So the length of the pencil is 4.3 cm.
Explain with an example of how you will use the metre ruler in part (a) if the ends of a ruler are broken.
Ans. The ends of the ruler get damaged with use and its zero marks may not be visible. To measure the length of an object with such a ruler, the object is placed close to a specific marking on the ruler and positions of both ends of the object are read on the ruler.
The difference between the two readings gives the length of the object. In fig. the reading on the ruler at the end X is 1.0 cm and at the end, Y is 4.3 cm. So the length of the rod XY is 4.3 — 1.0 = 3.3 cm.
APPEARS IN
RELATED QUESTIONS
Fill in the blank:
The S.I. unit of length is ............ of time is ............ of mass is ............
State if the following statement is true or false:
In ancient times, a cubit was used to measure the mass of an object.
Name the device used to measure the following:
Size of your shoulder.
Name the device used to measure the following:
Your height.
Name the device used to measure the following:
Your weight.
State two precautions to be observed while measuring length with the help of a metre scale.
The area can be calculated by using the two lengths and width.
SI unit of length is ______.
Four children measure the length of a table which was about 2 m. Each of them used different ways to measure it.
- Sam measured it with a half metre long thread.
- Gurmeet measured it with a 15 cm scale from her geometry box.
- Reena measured it using her hand span.
- Salim measured it using a 5 m long measuring tape.
Which one of them would get the most accurate length? Give reason for your answer.
While travelling in a train, it appears that the trees near the track are moving whereas co-passengers appear to be stationary. Explain the reason.
