Which statement about the dark nebulae is true? (a) they can be penetrated only with shorter waves, such as uv and x-ray.(b) they can be penetrated only with longer wavelengths such as radio and infrared. (c) they block the vast majority of radio waves from our galaxy.(d) only one is known to exist.(e) hydrogen and helium are the chief absorbing and scattering agents.

(B) They can be penetrated only with longer wavelengths such as radio and infrared.

Explanation:

A dark nebula is a type of interstellar cloud with such a high density that it "hides" the light of the background stars.

It should be noted that these nebulae are composed mostly of hydrogen (the star's primary fuel), and the absence of light (in the visible range of the electromagnetic spectrum) is caused by the interstellar solid dust that constitutes the cloud, which is why they are also called absorption nebulae.

However, if powerful telescopes that detect at long wavelengths, such as infrared and X-rays, it is possible to observe through these nebulae and even observe the existence of young stars.

acceleration = (change in speed) / (time for the change)

change in speed = (20-120)= -100 m/s.

1.5 min = 90 sec

acceleration = -100/90 = -1.11 m/s^2.

we don't care about the 150kg or the 2,500 meters. they don't make any difference.

read more on -