Earth's atmosphere is a <em>mixture</em> of gases that have
not reacted to become chemical compounds.
Sadly, we're forced to answer the question without the benefit of the
list of choices, which, for some reason, you decided not to let us see.
Index of refraction of a substance =
(speed of light in vacuum) / (speed of light in the substance).
Any number greater than ' 1 ' can be an index of refraction. A number
less than ' 1 ' can't be . . . that would be saying that the speed of light
in this substance is greater than the speed of light in vacuum.
Answer:
POSITIVE
Explanation:
The acceleration of an object is given by the rate of change of velocity.
u and v are initial and final velocities
If the final velocity is more than that of the initial velocity, the acceleration of the object is positive. It means positive acceleration occurs when an object speeds up. Hence, the correct option is (a) "positive".
You're in luck ! This is gonna be easy. Listen to this:
On the exam, they're gonna put questions about all that same stuff
that they talked about IN the class all those times ! The exact same
material. And if they didn't talk about it in class, then it won't be on
the exam ! How cool is that ? !
All that stuff you copied from the board, all those notes you wrote in
your notebook so you'd remember it, all those handouts they gave out
in class, all that homework you did ... THAT's what they'll put on the exam !
It's gonna be all stuff that you seen and heard and studied before.
No surprises. It'll be a breeze, and you're totally gonna do fine.
High-frequency sound waves have a shorter wavelength and a higher pitch than low-frequency sound waves.
