Answer:3.51
Explanation:
Given
Coefficient of Friction 
Consider a small element at an angle \theta having an angle of 
Normal Force
Friction 
and 
If my math is right its A) 7
because 189 divided by 27 is 7
If a star is moving towards Earth, shift towards the blue end of the spectrum, this is called blue shift. If the star is moving away from Earth the light from that star will be red and is called red shift .
The faster a star moves towards the earth, the more its light is shifted to higher frequencies. In contrast, if a star is moving away from the earth, its light is shifted to lower frequencies on the color spectrum
if a star is moving towards Earth, it appears to emit light that is shorter in wavelength compared to a source of light that isn't moving. Because shorter wavelengths correspond to a shift towards the blue end of the spectrum, this is called blue shift.
If the star is moving away from Earth, its light will lose energy to reach Earth, therefore the light from that star will be red and is called red shift
learn more about blue shift :
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Answer:
The action of rotating around something like for ex.. Child A stands in the middle of a room while Child B goes around Child A, Child B is rotating around Child A. Another ex. is; The earth rotates around the sun every 365 days the earth is rotating or going around the sun in a circle. So rotating to me is the act of rotating around something in any way shape or form.
PS: A middle schooler answered this so if you don't wanna believe me or think I'm wrong because I am younger you do you.
