Advertisements
Advertisements
Question
Guess the lengths to draw these things. Ask your friend to draw the same. After you make the drawing use a scale to measure the length. Whose drawing showed a better guess?
| Guess its length and draw |
Measure of your drawing |
Measure of your friend’s drawing |
| An ant of length less than 1 cm |
||
| Pencil of length about 7 cm |
||
| A glass 11 cm high with water up to 5 cm |
||
| A bangle of perimeter 20 cm |
||
| A curly hair of length 16 cm |
Advertisements
Solution
| Guess its length and draw |
Measure of your drawing |
Measure of your friend’s drawing |
| An ant of length less than 1 cm |
0.8 cm | 1.4 cm |
| Pencil of length about 7 cm |
6.4 cm | 7.2 cm |
| A glass 11 cm high with water up to 5 cm |
10.5 cm and 4.6 cm | 8 cm and 4.5 cm |
| A bangle of perimeter 20 cm |
18.9 cm | 20.2 cm |
| A curly hair of length 16 cm |
15 cm | 16.6 cm |
APPEARS IN
RELATED QUESTIONS
Just as precise measurements are necessary in science, it is equally important to be able to make rough estimates of quantities using rudimentary ideas and common observations. Think of ways by which you can estimate the following (where an estimate is difficult to obtain, try to get an upper bound on the quantity):-
the number of air molecules in your classroom.
Exercise
Answer the following question.
Star A is farther than star B. Which star will have a large parallax angle?
500 gm = ______ kilogram.
Ten millimetre makes one centimetre.
A hand span is a reliable measure of length.
Match the following.
| 1. | Length of the fore arm | metre |
| 2. | SI unit of length | second |
| 3. | Nano | 103 |
| 4. | SI Unit of time | 10–9 |
| 5. | Kilo | Cubit |
Find the answer for the following questions within the grid.

- 10-3 is one ______
- SI Unit of time is ______
- Cross view of reading a measurement leads to ______
- ______ is the one what a clock reads.
- ______ is the amount of substance present in an object.
- ______ can be taken to get the final reading of the recordings of different students for a single measurement.
- ______ is a fundamental quantity.
- ______ shows the distance covered by an automobile
- A tailor uses ______ to take measurements to stitch the cloth.
- Liquids are measured with this physical quantity.
Have you seen frogs? Where? How many different types of frogs have you seen? Are all the frogs of the same length? Here are two interesting examples.

How many stamps are needed to cover the rectangle?
How close was your earlier guess? Discuss.
There are two beautiful lakes near a village. People come for boating and picnics in both the lakes. The village Panchayat is worried that with the noise of the boats the birds will stop coming. The Panchayat wants motorboats in only one lake. The other lake will be saved for the birds to make their nests.

- How many kilometers long is the actual boundary of lake A?
What are the materials needed to find the length of a banana?
What formula is used to measure the area of your classroom?
Match the following:
| Prefix | Symbol | ||
| a. | Centi | i. | k |
| b. | Nano | ii. | c |
| c. | Mili | iii. | n |
| d. | Kilo | iv. | m |
In the parallax formula D = b/θ, what must be true about the angle θ for the calculation to be correct?
If a planet subtends an angle α at distance D, what formula is used to find the planet's diameter?
