Answer:
B) waves speed up
C) waves bend away from the normal
Explanation:
The index of refraction of a material is the ratio between the speed of light in a vacuum and the speed of light in that medium:

where
c is the speed of light in a vacuum
v is the speed of light in the medium
We can re-arrange this equation as:

So from this we already see that if the index of refraction is lower, the speed of light in the medium will be higher, so one correct option is
B) waves speed up
Moreover, when light enters a medium bends according to Snell's Law:

where
are the index of refraction of the 1st and 2nd medium
are the angles made by the incident ray and refracted ray with the normal to the interface
We can rewrite the equation as

So we see that if the index of refraction of the second medium is lower (
), then the ratio
is larger than 1, so the angle of refraction is larger than the angle of incidence:

This means that the wave will bend away from the normal. So the other correct option is
C) waves bend away from the normal
<span>d. The parallaxes beyond a few thousand light years are
too small to be measured with common instruments.
I'm not sure that parallax can even be used out to a few
thousand light years.
The NEAREST star to Earth has the BIGGEST parallax.
The star is Alpha Centauri. It's only 4 light years away
from us, and its parallax is 0.000206 of a degree !
I have no idea how astronomers can measure angles
so small ... and that's the BIGGEST parallax angle of
ANY star.</span>
To develop this problem we will apply the considerations made through the concept of Doppler effect. The Doppler effect is the change in the perceived frequency of any wave movement when the emitter, or focus of waves, and the receiver, or observer, move relative to each other. At first the source is moving towards the observer. Than the perceived frequency at first

Where F is the actual frequency and v is the velocity of the ambulance
Now the source is moving away from the observer.

We are also so told the perceived frequency decreases by 11.9%



Equating,





Solving for V,

Helium and nitrogen because they are both from the noble gas group.
Answer:
The net force acting on the otter along the incline is 13.96 N.
Explanation:
It is given that,
Mass of the otter, m = 2 kg
Distance covered by otter, d = 85 cm = 0.85 m
It takes 0.5 seconds.
We need to find the net force acts on the otter along the incline. If a is the acceleration of the otter. It can be calculated using second equation of motion as :

Here, u = 0 (at rest)




The net force acting on the otter along the incline is given by :
F = ma

F = 13.6 N
So, the net force acting on the otter along the incline is 13.96 N. Hence, this is the required solution.