Acommunications satellite with a mass of 420 kg is in a circular orbit about the earth. the radius of the orbit is 2.9×10^4 km as measured from the center of the earth. calculate (a) the weight of the satelitte on the surface of the earth and (b) the gravitational force exerted on the satellite by the earth when it is in orbit.

To solve this problem we will apply the concepts related to Newton's second law that will allow us to find the Weight of the object, and the law of universal gravitation raised by it, in order to find it at a certain point.

Part A) We know the acceleration due to gravity on the surface:

F=m*a

Where,

m = mass

a = Gravitational acceleration

Therefore the weight of the satellite on the surface of the earth is 4.1kN

Part B) To find the acceleration due to gravity at 29*10^3 km above the earth's center, we need to use Newton's law of universal gravitation:

Where,

G = Gravitational universal constant

M = Mass of Earth

m = Mass of the object

r = Distance from center of Earth

Replacing,

Therefore the gravitational force exerted on the satellite by the Earth when it is in orbit is 198.8N

the word that best describes martin luther king jr.'s tone in the video is dignified

martin luther king, jr. was a social activist and baptist minister who played a key role in the american civil rights movement from the mid-1950s until his assassination in 1968. the video shows his manner and attitude having or showing a composed or serious manner that is worthy of respect so dignified is the correct answer

scattering of light by tiny particles in air to produce the colors we see on sky, is dependent on the following factors:

(i) wavelength of light

(ii) size of the scattering particle  

(iii) distance traveled by light through the atmosphere.

according to rayleigh's law of scattering, the amount of scattering is inversely proportional to the fourth power of its wavelength. shorter the wavelength, greater is its scattering. hence violet/blue light is scattered more than red.

sun's light is a composite light ( visible light) with wavelengths in the range 400 nm (violet) to 700 nm (red). as sunlight passes through our atmosphere, the molecules of air scatter light according to their wavelengths. during sunrise and sunset, the sun's position is below the horizon. hence light from the sun travels a greater distance in the atmosphere when compared to its position a noon.

as sunlight enters the earth's atmosphere, blue light is scattered away and at the end of its journey in the sky, only red and orange wavelengths remain in the beam.

hence at sunrise and sunset, the sky appears reddish orange.