Answer:
Contact glasses.
Explanation:
-Anytime you put on a pair of glasses, or see light bend through a glass of water or a prism, this rule is in action.
-In short, Snell's law governs the angle by which electromagnetic radiation such as light refracts, or changes direction, as it passes from one material to another and slows down.
11. protect the cell and keep its shape.
12. chloroplast
For a cylinder that has both ends open resonant frequency is given by the following formula:

Where n is the resonance node, v is the speed of sound in air and L is the length of a cylinder.
The fundamental frequency is simply the lowest resonant frequency.
We find it by plugging in n=1:

To find what harmonic has to be excited so that it resonates at f>20Hz we simply plug in f=20 Hz and find our n:

We can see that any resonant frequency is simply a multiple of a base frequency.
Let us find which harmonic resonates with the frequency 20 Hz:

Since n has to be an integer, final answer would be 323.
Answer:
a=g.
the body is in one of these INGRAVIDITY, so the weight of the body would be ZERO
Explanation:
When the spacecraft revolves around the Earth, it is subjected to Newton's second law
F = m a
where the force is the universal attractive force, the mass of the astronauts, and the centripetal acceleration.
a = F / m
a = (G M m / r²) / m
a = G M / r²
the amount of is the acceleration of gravity at height r.
a = g
Therefore, we see that the acceleration of the body is equal to the acceleration of gravity, which is why the body is in one of these INGRAVIDITY, so the weight of the body would be ZERO
Answer: 
Explanation:
Given the mass of skier m=72 kg
distance traveled d=75 m
constant speed v=3.4 m/s
If speed is constant then there must no force acting in the direction of motion
i.e. tension force must be equal to the component of weight

Work done is given by