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Sergeeva-Olga [200]
3 years ago
10

The first international standard of length was a metal bar kept at the International Bureau of Weights and Measures. One meter o

f length was defined to be the distance between two fine lines engraved near the ends of the bar. Why was it important that the bar be kept at a constant temperature?
Physics
1 answer:
anyanavicka [17]3 years ago
7 0

Answer:

International Bureau of Weights and Measures have the standard bar for one meter length and it is made up of the platinium-iridium alloy. As these are metals so they have the thermal expansion. So the length of the bar depends upon the temperature. Temperature changes can effect the length of the standard bar. That's reason behind keeping the bar at the constant temperature as the change in temperature will result in the change of length.

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If Star A is magnitude 1.0 and Star B is magnitude 9.6 , which is brighter and by what factor?
ludmilkaskok [199]

Answer:

Star A is brighter than Star B by a factor of 2754.22

Explanation:

Lets assume,

the magnitude of star A = m₁ = 1

the magnitude of star B = m₂ = 9.6

the apparent brightness of star A and star B are b₁ and b₂ respectively

Then, relation between the difference of magnitudes and apparent brightness of two stars are related as give below: (m_{2} - m_{1}) = 2.5\log_{10}(b_{1}/b_{2})

The current magnitude scale followed was formalized by Sir Norman Pogson in 1856. On this scale a magnitude 1 star is 2.512 times brighter than magnitude 2 star. A magnitude 2 star is 2.512 time brighter than a magnitude 3 star. That means a magnitude 1 star is (2.512x2.512) brighter than magnitude 3 bright star.

We need to find the factor by which star A is brighter than star B. Using the equation given above,

(9.6 - 1) = 2.5\log_{10}(b_{1}/b_{2})

\frac{8.6}{2.5}  = \log_{10}(b_{1}/b_{2})

\log_{10}(b_{1}/b_{2}) = 3.44

Thus,

(b_{1}/b_{2}) = 2754.22

It means star A is 2754.22 time brighter than Star B.

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it took 3.5 hours for a train to travel the distance between two cities at a velocity of 120 miles per hour. How many miles lie
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Given:

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