Answer:
1. Luminosity
2.Apparent brightness
Explanation:
There are two factors on which brightness of star appear to be in the sky
The two factors are
1. Luminosity
2.Apparent brightness
1.Luminosity :It is defined as the total energy emitted by the object in a given time.Luminosity vary with the distance of observer from the star.Luminosity is a intrinsic property which depends on the fundamental chemical composition and structure of the material.Luminosity is depends on the size of star.Lager the star luminosity will be more.
2.Apparent brightness: It is defined as how bright a star appears from an observer on the earth and the amount of starlight reaching the earth.if the distance is large then the brightness decreases.When the distance of star from us small then the brightness of star increases.Distance is inversely proportional to brightness of the star.
Answer:
Characteristic numbers are dimensionless numbers used in fluid dynamics to describe a character of the flow. To compare a real situation with a small-scale model it is necessary to keep the important characteristic numbers the same. Names of these numbers were standardized in ISO 31, part 12.
Explanation:
92 percent because you multiply it by 2
Answer:
part (a) 
part (b) N = 79.61 rev
part (c) 
Explanation:
Given,
- Initial speed of the wheel =

- total time taken = t = 20.0 sec
part (a)
Let
be the angular acceleration of the wheel.
Wheel is finally at the rest. Hence the final angular speed of the wheel is 0.

part (b)
Let
be the total angular displacement of the wheel from initial position till the rest.

We know, 1 revolution =
rad
Let N be the number of revolution covered by the wheel.

Hence the 79.61 revolution is covered by the wheel in the 20 sec.
part (c)
Given,
- Mass of the pole = m = 4 kg
- Length of the pole = L = 2.5 m
- Angle of the pole with the horizontal axis =

Now the center of mass of the pole = 
Weight component of the pole perpendicular to the center of mass = 

Answer:
KE = 11,719 J
Explanation:
KE = ½ mv²
KE = ½ (1.5 kg) (125 m/s)²
KE = 11,719 J