Which statement correctly describes variable stars?

Physics

1 answer:

Kryger [21]3 years ago

5 0

Answer:

Explanation:

The Period-Luminosity relationship tells us that luminosity increases with the period, and of course the more luminosity a star has the more far away they can be seen, so from this we know that:

A) False since lower luminosities can be observed when they are close.

B) False since longer periods means higher luminosities

C) False since lower luminosities can be observed when they are close.

D) True: Variable stars with shorter periods have lower luminosities, so they can only be observed when they are close.

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Two students walk in the same direction along a straight path, at a constant speedâone at 0.90 m/s and the other at 1.90 m/s.

mixer [17]

Answer:

456.143684211 seconds

564.3 m

Explanation:

s = Distance

v = Velocity

Time is given by

$t=\dfrac{s}{v}\\\Rightarrow t=\dfrac{780}{0.9}\\\Rightarrow t=866.67\ s$

$t=\dfrac{s}{v}\\\Rightarrow t=\dfrac{780}{1.9}\\\Rightarrow t=410.526315789\ s$

Difference in time = 866.67-410.526315789 = 456.143684211 seconds

According to the question

$\dfrac{x}{0.9}-\dfrac{x}{1.9}=5.5\times 60\\\Rightarrow x(\dfrac{1}{0.9}-\dfrac{1}{1.9})=330\\\Rightarrow x=\dfrac{330}{\dfrac{1}{0.9}-\dfrac{1}{1.9}}\\\Rightarrow x=564.3\ m$