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प्रश्न
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!!
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उत्तर
Area of 30 m × 20 m rectangle = 600 square metres
Its area is larger than the area of the first rectangle.
The other rectangles that he can make with 100 metres of wire are
40 m × 10 m,
48 m × 2 m,
49 m × 1 m,
45 m × 5 m
- A
As the area of a rectangle, A is shown as 40 m × 20 m.
So, the length of rectangle = 40 m
Width of rectangle = 20 m
Gold wire for A
= 40 + 20 + 40 + 20
= 120 metres - B
As the area of rectangle B is shown as 80 m × 10 m.
So, the length of rectangle = 80 m
Width of rectangle = 10 m
Gold wire for B
= 80 + 10 + 80 + 10
= 180 metres - C
As the area of rectangle C is shown as 800 m × 1 m.
So, the length of rectangle = 800 m
Width of rectangle = 1 m
Gold wire for C
= 800 + 1 + 800 + 1
= 1602 metres - D
As the area of rectangle D is shown as 8000 m × 0.1 m.
So, the length of rectangle = 8000 m
Width of rectangle = 0.1 m
Gold wire for C
= 8000 + 0.1 + 8000 + 0.1
= 16000 + 0.2
= 16000.2 metres.
So, he will get 16000.2 metres of gold wire!!
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?
When the planet Jupiter is at a distance of 824.7 million kilometres from the Earth, its angular diameter is measured to be 35.72″ of arc. Calculate the diameter of Jupiter
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 strands of hair on your head
Match the following.
| Column A | Column B |
| (1) Length | a. kilogram |
| (2) Mass | b. cubic metre |
| (3) Area | c. metre |
| (4) Volume | d. square metre |
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.
Rulers, measuring tapes and metre scales are used to measure ______
You can play this game on the ground. Make two squares of one square meter each. Divide your class into two teams. Ready to play!
- Which team could make more children sit in their square? How many?
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 cm is the length of the boundary of lake A in the drawing?(use thread to find out)
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 B?
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.
- A longer boundary around the lake will help more birds to lay their eggs. So which lake should be kept for birds? Which lake should be used for boats?
Give some examples of larger length measures.
What is the unit of measurements of very small lengths?
Larger unit for measuring time is ______.
- The earth-moon distance is about 60 earth radius. What will be the diameter of the earth (approximately in degrees) as seen from the moon?
- Moon is seen to be of (½)°diameter from the earth. What must be the relative size compared to the earth?
- From parallax measurement, the sun is found to be at a distance of about 400 times the earth-moon distance. Estimate the ratio of sun-earth diameters.
According to the modern definition, what fraction of a second does light travel to define one metre?
If a planet subtends an angle α at distance D, what formula is used to find the planet's diameter?
One parsec is defined as ______.
The parallax method is used to measure astronomical distances because ______.
