Answer: (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, <u>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.</u>
Jets and planes can fly in the stratophere
You have to make sure you know what your doing plus if you have your license and stuff to fly you have to practice on a 25 minute course
I think WA in friction means Water Absorption.
Answer:
Part a)

Part b)
force is 21.2 times more than the weight of the person
Explanation:
Part a)
As it is given that the distance after which he stopped is given as
d = 1.50 cm
here finally it stops so final speed is given as

initial speed is given as

now by the equation of kinematics we know that



Now the force on the leg is given as

m = mass of leg = 13 kg


Part b)
Force due to weight of the object

here we know
M = 75.0 kg


Now we know that the ratio of the weight with the force on leg is given as

so force is 21.2 times more than the weight of the person