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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 |
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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 |
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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?
Answer the following question.
Star A is farther than star B. Which star will have a large parallax angle?
Solve the numerical example.
When the planet Jupiter is at a distance of 824.7 million kilometers from the Earth, its angular diameter is measured to be 35.72'' of arc. Calculate the diameter of Jupiter.
While measuring the length of an object using a ruler, the position of your eye should be
Fill in the following chart.
| Property | Definition | Basic Unit | Instrument used for measuring |
| Length | |||
| Mass | |||
| Volume | |||
| Time |
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?
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How close was your earlier guess? Discuss.
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How long is your belt? _________
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Length is ______.
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According to the modern definition, what fraction of a second does light travel to define one metre?
In the parallax formula D = b/θ, what must be true about the angle θ for the calculation to be correct?
