Advertisements
Advertisements
प्रश्न
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
उत्तर
| 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
संबंधित प्रश्न
The principle of ‘parallax’ in section 2.3.1 is used in the determination of distances of very distant stars. The baseline AB is the line joining the Earth’s two locations six months apart in its orbit around the Sun. That is, the baseline is about the diameter of the Earth’s orbit ≈ 3 × 1011m. However, even the nearest stars are so distant that with such a long baseline, they show parallax only of the order of 1” (second) of arc or so. A parsec is a convenient unit of length on the astronomical scale. It is the distance of an object that will show a parallax of 1” (second) of arc from opposite ends of a baseline equal to the distance from the Earth to the Sun. How much is a parsec in terms of meters?
The nearest star to our solar system is 4.29 light years away. How much is this distance in terms of parsecs? How much parallax would this star (named Alpha Centauri) show when viewed from two locations of the Earth six months apart in its orbit around the Sun?
Exercise
Answer the following question.
Star A is farther than star B. Which star will have a large parallax angle?
500 gm = ______ kilogram.
Rulers, measuring tapes and metre scales are used to measure ______
Assertion (A): Distance between two celestial bodies is measured in terms of light year.
Reason (R): The distance travelled by the light in one year is one light year.
Can you find the diameter of a thin wire of length 2 m using the ruler from your instrument box?
Guess whose tail is the longest. Now measure the tails. How good is your guess?
Arbaz plans to tile his kitchen floor with green square tiles. Each side of the tile is 10 cm. His kitchen is 220 cm in length and 180 cm wide. How many tiles will he need?
Now cut strips of equal sizes out of it. Using tape join the strips, end to end, to make a belt.
How long is your belt? _________
Can you think of how to cut a postcard so that you can pass through it?
So Anar also tried many different ways to make a boundary for 800 square meters of land.
He made rectangles A, B, and C of different sizes. Find out the length of the boundary of each. How much gold wire will he get for these rectangles?
- A
Gold wire for A = _________ metres - B
Gold wire for B = _________ metres - C
Gold wire for C = __________ metres
But then Anar made an even longer rectangle... See how long!
- D
So he will get __________ metres of gold wire!!
Length is a fundamental quantity.
What are the materials needed to find the length of a banana?
Give some examples of larger length measures.
What is the unit of measurements of very small lengths?
Length is ______.
What unit will you use to measure the length of our classroom?
The distance of a galaxy is of the order of 1025 m. Calculate the order of magnitude of time taken by light to reach us from the galaxy.
