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Evgen [1.6K]
3 years ago
12

An atom of a certain element has 36 protons, 36 electrons, and a mass number of 84. At room temperature, this element is a very

stable gas. How many neutrons are in this atom?
Physics
1 answer:
Grace [21]3 years ago
5 0

Answer:

12 neutrons

Explanation:

The number of protons also shows the atomic number. Therefore the element in question is Krypton (Kr), which also is a noble gas.

Neutrons = Mass number - protons - electrons

Here neutrons = 84 - 36 - 36 = 12

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At the same moment, one rock is dropped and one is theown downwand with an iniial velocily of 29 us frm op of a building that is
Helen [10]

Answer:

The thrown rock will strike the ground 2.42s earlier than the dropped rock.

Explanation:

<u>Known Data</u>

  • y_{i}=300m
  • y_{f}=0m
  • v_{iD}=0m/s
  • v_{iT}=-29m/s, it is negative as is directed downward

<u>Time of the dropped Rock</u>

We can use y_{f}=y_{i}+v_{iy}t-\frac{gt^{2}}{2}, to find the total time of fall, so 0=300m-\frac{(9.8m/s^{2})t_{D}^{2}}{2}, then clearing for t_{D}.

t_{D}=\sqrt[2]{\frac{300m}{4.9m/s^{2}}} =\sqrt[2]{61.22s^{2}} =7.82s

<u>Time of the Thrown Rock</u>

We can use y_{f}=y_{i}+v_{iy}t-\frac{gt^{2}}{2}, to find the total time of fall, so 0=300-29t_{T}-\frac{(9.8)t_{T}^{2}}{2}, then, 0=-4.9t_{T}^{2}-29t_{T}+300, as it is a second-grade polynomial, we find that its positive root is t_{T}=5.4s

Finally, we can find how much earlier does the thrown rock strike the ground, so t_{E}=t_{D}-t_{T}=7.82s-5.4s=2.42s

6 0
3 years ago
The maximum speed with which you can throw a stone is about 20 m/s. Can you hit a window 45 m away horizontally and 10 m up from
Allushta [10]

Answer:

 y = 17 m

Explanation:

For this projectile launch exercise, let's write the equation of position

          x = v₀ₓ t

          y = v_{oy} t - ½ g t²

let's substitute

          45 = v₀ cos θ t

          10 = v₀ sin θ t - ½ 9.8 t²

the maximum height the ball can reach where the vertical velocity is zero

 

           v_{y} = v_{oy} - gt

           0 = v₀ sin θ - gt

           0 = v₀ sin θ - 9.8 t

Let's write our system of equations

         45 = v₀ cos θ  t

         10 = v₀ sin θ t - ½ 9.8 t²

         0 = v₀ sin θ - 9.8 t

We have a system of three equations with three unknowns for which it can be solved.

Let's use the last two

        v₀ sin θ = 9.8 t

we substitute

        10 = (9.8 t) t - ½ 9.8 t2

        10 = ½ 9.8 t2

        10 = 4.9 t2

        t = √ (10 / 4.9)

        t = 1,429 s

Now let's use the first equation and the last one

         45 = v₀ cos θ t

         0  = v₀ sin θ - 9.8 t

         9.8 t = v₀  sin θ

         45 / t = v₀ cos θ

we divide

         9.8t / (45 / t) = tan θ

          tan θ = 9.8 t² / 45

          θ = tan⁻¹ ( 9.8 t² / 45 )

          θ = tan⁻¹ (0.4447)

          θ = 24º

Now we can calculate the maximum height

         v_y² = v_{oy}^2 - 2 g y

         vy = 0

          y = v_{oy}^2 / 2g

          y = (20 sin 24)²/2 9.8

          y = 3,376 m

the other angle that gives the same result is

       θ‘= 90 - θ

       θ' = 90 -24

       θ'= 66'

for this angle the maximum height is

 

          y = v_{oy}^2 / 2g

          y = (20 sin 66)²/2 9.8

           y = 17 m

thisis the correct

6 0
3 years ago
Make a
defon

Answer:

Yes, a mixture can be made up of just elements and no compounds. The elements never experiance a chemical interaction and stay only in physical contact with each other.

BRAILIEST PLS I NEED LEVEL UP!

3 0
3 years ago
The chemical symbol for the element calcium is Ca. What would be the symbol representing calcium atoms that have lost two electr
Kazeer [188]

Answer:

ca^{2 + }

Explanation:

In all atoms, the number of protons = number of electrons, as a result the atom is neutral. Losing or gaining electrons will make the atom electrically charged and we call an electrically charged atom an ion.

Ca 2+ would be the symbol because losing two negative electrons makes calcium's nucleus more positive by two protons.

5 0
3 years ago
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Describe how transverse waves can be produced by a rope. Then describe hiw pieces of the rope move as waves pass.
Oduvanchick [21]
We did this experiment before, when the rope moves, it represents the waves passing through in from the level of intensity. I hope this is a good answer.
3 0
3 years ago
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