The answer is C. in sort of a way. You can't technically see black matter. However, it is holding the galaxies together.
It totally depends on what kind of wave you're talking about.
-- a sound wave from a trumpet or clarinet playing a concert-A pitch is about 78 centimeters long ... about 2 and 1/2 feet. This is bigger than atoms.
-- a radio wave from an AM station broadcasting on 550 KHz, at the bottom of your radio dial, is about 166 feet long ... maybe comparable to the height of a 10-to-15-story building. This is bigger than atoms.
-- a radio wave heating the leftover meatloaf inside your "microwave" oven is about 4.8 inches long ... maybe comparable to the length of your middle finger. this is bigger than atoms.
-- a deep rich cherry red light wave ... the longest one your eye can see ... is around 750 nanometers long. About 34,000 of them all lined up will cover an inch. These are pretty small, but still bigger than atoms.
-- the shortest wave that would be called an "X-ray" is 0.01 nanometer long. You'd have to line up 2.5 billion of <u>those</u> babies to cover an inch. Hold on to these for a second ... there's one more kind of wave to mention.
-- This brings us to "gamma rays" ... our name for the shortest of all electromagnetic waves. To be a gamma ray, it has to be shorter than 0.01 nanometer.
Talking very very very very roughly, atoms range in size from about 0.025 nanometers to about 0.26 nanometers.
The short end of the X-rays, and on down through the gamma rays, are in this neighborhood.
Answer:
<em>The penny will hit the ground at 6.39 seconds</em>
Explanation:
<u>Free Fall</u>
The penny is dropped from a height of y=200 m. The equation of the height on a free-fall motion is given by:
Where 
, and t is the time.
Solving for t:
Using the value y=200:
t=6.39 sec
The penny will hit the ground at 6.39 seconds
Answer:
Explanation:
Given:
- cross sectional area of the wire,
- density of aluminium wire,
- young's modulus of the material,
- wave speed,
<u>We have mathematical expression for strain as:</u>
...............................(1)
and since, 
where, T = tension force in the wire
equation (1) becomes:
............................(2)
<u>Also velocity ofwave in tensed wire:</u>
...................................(3)
where: 
linear mass density of the wire
Now, equation (3) becomes
............................(4)
Using eq. (2) & (4) for tension T
putting the respective values
Answer:
Explanation:
m₂ is hanging vertically and m₁ is placed on inclined plane . Both are in limiting equilibrium so on m₁ , limiting friction will act in upward direction as it will tend to slip in downward direct . Tension in cord connecting the masses be T .
For equilibrium of m₁
m₁ g sinα= T + f where f is force of friction
m₁ g sinα= T + μsx m₁ g cosα
m₁ g sinα - μs x m₁ g cosα = T
For equilibrium of m₂
T = m₂g
Putting this value in equation above
m₁ g sinα - μs x m₁ g cosα = m₂g
m₂ = m₁ sinα - μs x m₁ cosα
