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प्रश्न
A particular star is at a distance of about 8.1 × 1013 km from the Earth. Assuring that light travels at 3 × 108 m per second, find how long does light takes from that star to reach the Earth.
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उत्तर
The distance between Star and Earth = 8.1 × 1013 km = 8.1 × 1013 × 103 m
Since, light travels at 3 × 108 m per second.
So, time taken by light to reach the Earth = `(8.1 xx 10^13 xx 10^3)/(3 xx 10^8)`
= `(8.1 xx 10^16)/(3 xx 10^8)`
= `8.1/3 xx 10^8`
= 2.7 × 108 s
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संबंधित प्रश्न
The diameter of the Sun is 1.4 × 109 m and the diameter of the Earth is 1.2756 × 107 m.
The table shows the average distance from each planet in our solar system to the sun.
| Planet | Distance from Sun (km) |
Distance from Sun (km) Standard Notation |
| Earth | 149,600,000 | 1.496 × 108 |
| Jupiter | 778,300,000 | |
| Mars | 227,900,000 | |
| Mercury | 57,900,000 | |
| Neptune | 4,497,000,000 | |
| Pluto | 5,900,000,000 | |
| Saturn | 1,427,000,000 | |
| Uranus | 2,870,000,000 | |
| Venus | 108,200,000 |
- Complete the table by expressing the distance from each planet to the Sun in scientific notation.
- Order the planets from closest to the sun to farthest from the sun.
Similarly, repeater machine is a hypothetical machine which automatically enlarges items several times. For example, sending a piece of wire through a (× 24) machine is the same as putting it through a (× 2) machine four times. So, if you send a 3 cm piece of wire through a (× 24) machine, its length becomes 3 × 2 × 2 × 2 × 2 = 48 cm. It can also be written that a base (2) machine is being applied 4 times.
What will be the new length of a 4 cm strip inserted in the machine?
For the following repeater machines, how many times the base machine is applied and how much the total stretch is?
Find three repeater machines that will do the same work as a (× 64) machine. Draw them, or describe them using exponents.
What will the following machine do to a 2 cm long piece of chalk?
Ajay had a 1 cm piece of gum. He put it through repeater machine given below and it came out `1/(100,000)` cm long. What is the missing value?
Shikha has an order from a golf course designer to put palm trees through a (× 23) machine and then through a (× 33) machine. She thinks she can do the job with a single repeater machine. What single repeater machine should she use?
Neha needs to stretch some sticks to 252 times their original lengths, but her (× 25) machine is broken. Find a hook-up of two repeater machines that will do the same work as a (× 252) machine. To get started, think about the hookup you could use to replace the (× 25) machine.
The left column of the chart lists the lengths of input pieces of ribbon. Stretching machines are listed across the top. The other entries are the outputs for sending the input ribbon from that row through the machine from that column. Copy and complete the chart.
| Input Length | Machine | |||
| × 2 | ||||
| 1 | 5 | |||
| 3 | 15 | |||
| 14 | 7 | |||
