Answer:
Vf = 210 [m/s]
Av = 105 [m/s]
y = 2205 [m]
Explanation:
To solve this problem we must use the following formula of kinematics.

where:
Vf = final velocity [m/s]
Vo = initial velocity = 0 (released from the rest)
g = gravity acceleration = 10 [m/s²]
t = time = 21 [s]
Vf = 0 + (10*21)
Vf = 210 [m/s]
Note: The positive sign for the gravity acceleration means that the object is falling in the same direction of the gravity acceleration (downwards)
The average speed is defined as the sum of the final speed plus the initial speed divided by two. (the initial velocity is zero)
Av = (210 + 0)/2
Av = 105 [m/s]
To calculate the distance we must use the following equation of kinematics

44100 = 20*y
y = 2205 [m]
Just like mass, energy, linear momentum, and electric charge, angular momentum is also conserved.
The wheel has angular momentum. I don't remember whether it's
up or down (right-hand or left-hand rule), but it's consistent with
counterclockwise rotation as viewed from above.
When you grab the wheel and stop it from spinning (relative to you),
that angular momentum has to go somewhere.
As I see it, the angular momentum transfers through you as a temporary
axis of rotation, and eventually to the merry-go-round. Finally, all the mass
of (merry-go-round) + (you) + (wheel) is rotating around the big common
axis, counterclockwise as viewed from above, and with the magnitude
that was originally all concentrated in the wheel.
The Balmer light series comes under the visible light.
<u>Explanation:</u>
The transition of electrons from higher to energy level with 2 as principal quantum number results in the spectral emission lines of hydrogen atom and this series of lines are known as Balmer series.
Mostly, these lines has the wavelength of more than 400 nm but lesser than 700 nm. Generally of the four categories namely, 410, 434, 486, 656 nm which comes under the type of visible light. So, it can be concluded that the Balmer series light falls under visible light.
In astronomy, Balmer lines occur in various stellar (celestial or astronomical) objects due to the higher content of hydrogen in the universe. Therefore, they are commonly seen and relatively strong when compared to other element lines.
Note: nm is nanometer (one billionth of a meter in length)
Answer:
Explanation:
The volume of the tank = 50 kton
50 kton = 5 × 10⁷ kg
Since 18 grams of water will contain: 10 electrons × 6.023 × 10²³
Then;
5× 10⁷ kg will contain 
= 1.67 × 10³⁴ electrons
(b)
Suppose:

Then;
10⁻⁶ of 

Thus, the number of high energy neutrinos which will interact with water is:
= 
= 
= 
For 1.67 × 10³⁴ electrons, the detection rate is:


= 9.668 per day