This procedure has been used to "weigh" astronauts in space:
a 42.5 kg chair is attached to a spring and allowed to oscillate. when it is empty, the chair takes 1.30 s to make one complete vibration. but with an astronaut sitting in it, with her feet off the floor, the chair now takes 2.54 s for one cycle.
what is the mass of the astronaut?

Mass of astronaut will be 119.7674 kg

Explanation:

We have given mass of the chair

When there is chair alone then time period of osculation

Now when astronaut sit on the chair then total mass

Now with astronaut time period is

For spring time period is given by

So

Squaring both side

Mass of astronaut will be 119.7674 kg

answer: d. a cme increases the amount of energy in the solar wind

explanation:

coronal mass ejections, also called cmes, are large clouds of plasma and magnetic field that erupt from the sun. only when the cloud is aimed at earth will the cme hit earth and therefore cause impacts. high-speed solar wind streams come from areas on the sun known as coronal holes.

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.