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3 years ago

In the symbol 4/2He the subscript 4 is the _____for helium and 2 is the subscript for helium

1 answer:

7 0

$^{4}_{2}}He$
The 4 signifies the atomic weight, and the 2 subscribes the element's atomic number(aka the number of protons in the atom).

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Food chains are made up of many_____________. HELP ASAP!!!!!

Mashcka [7]

Hello!

Possible answer could be Organisms

There are a lot of Organisms in the overall food chain.

Hope this helped!

4 0

3 years ago

Read 2 more answers

A temperature of 20°C is equal to °F.

babymother [125]

The temperature of 20°C is equal to 68.0°F

8 0

3 years ago

Read 2 more answers

A boy throws a ball of mass 0.22 kg straight upward with an initial speed of 29 m/s. When the ball returns to the boy, its speed

maksim [4K]

Answer:

The work is -67.76 J

Explanation:

The law of conservation of energy is considered one of one of the fundamental laws of physics and states that the total energy of an isolated system remains constant. except when it is transformed into other types of energy.

This is summed up in the principle that energy can neither be created nor destroyed in the universe, only transformed into other forms of energy.

In this case you must calculate the loss of kinetic energy. This loss is actually the work done against the resistive force in the air. Friction is the only force other than gravity that acts on the ball.

So, the loss of kinetic energy is $\frac{1}{2} *m*(vf^{2} -vi^{2} )$

You know:

mass=m=0.22 kg
Initial velocity of the ball: $vi= 29 \frac{m}{s}$

Final velocity of the ball: $vf= 15 \frac{m}{s}$

Replacing:

$\frac{1}{2} *0.22 kg*(15^{2} -29^{2} )$ = -67.76 J

Friction work is always negative because friction is always against displacement.

The work is -67.76 J

5 0

3 years ago

A large container contains a large amount of water. A hole is drilled on the wall of the container, at a vertical distance h = 0

barxatty [35]

Answer:

Velocity = 3.25[m/s]

Explanation:

This problem can be solved if we use the Bernoulli equation: In the attached image we can see the conditions of the water inside the container.

In point 1, (surface of the water) we have the atmospheric pressure and at point 2 the water is coming out also at atmospheric pressure, therefore this members in the Bernoulli equation could be cancelled.

The velocity in the point 1 is zero because we have this conditional statement "The water surface drops very slowly and its speed is approximately zero"

h2 is located at point 2 and it will be zero.

$(P_{1} +\frac{v_{1}^{2} }{2g} +h_{1} )=(P_{2} +\frac{v_{2}^{2} }{2g} +h_{2} )\\P_{1} =P_{2} \\v_{1}=0\\h_{2} =0\\v_{2}=\sqrt{0.54*9.81*2}\\v_{2}=3.25[m/s]$

4 0

3 years ago

Radiation emitted from human skin reaches its peak at λ = 960 µm. what is the frequency of this radiation? planck's constant is

Artist 52 [7]

1) The wavelength of the radiation emitted by the human skin is
$\lambda=960 \mu m = 960 \cdot 10^{-6} m$
the frequency of the radiation is related to the wavelength by
$f= \frac{c}{\lambda}$
where $c=3 \cdot 10^8 m/s$ is the speed of light. Plugging numbers into the formula, we find the frequency of the radiation:
$f= \frac{3 \cdot 10^8 m/s}{960 \cdot 10^{-6}m}=3.13 \cdot 10^{11} Hz$

2) The frequency of this radiation is 313 GHz, and its wavelength $960 \mu m$ . If we look at the table of the electromagnetic spectrum
https://en.wikipedia.org/wiki/Electromagnetic_spectrum
We see that we are in the range of visible light (in particular, in the infrared range).
Therefore, the correct answer is 2. visible light .

6 0

3 years ago