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3 years ago

a subsrance has an atomic number of 80. How many protons and electrons do atoms of the substance have? what is the subsance?

Physics

1 answer:

valentinak56 [21]3 years ago

5 0

Answer:

The substance is Mercury. It has 80 electrons revolving around nucleus and 80 protons inside nucleus.

Explanation:

Atomic number of atom represent the number of electrons and protons of the atom. Thus,

Number of electrons = number of protons = 80

The atom which has atomic number 80 in the periodic table is Mercury.

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As the distance between two objects decreases, what happens to the force of gravity between the two objects

KonstantinChe [14]

The force of gravity between them increases.

3 0

4 years ago

Which of the following statements about electromagnetic waves in free space are true? (There could be more than one correct choi

Vanyuwa [196]

Answer:

The electric field carries the same mount of energy as the magnetic field

The frequency of the magnetic field is the same as the frequency of the electric field.

Explanation:

Let's analyze each option in detail:

The electric and magnetic fields have equal amplitudes. --> FALSE. In fact, the amplitudes of the electric and magnetic field are related by the equation:

$E=cB$

where

E is the amplitude of the electric field

B is the amplitude of the magnetic field

c is the speed of light

Therefore, from the equation we see that the amplitude of the electric field is much larger than that of the magnetic field.

The electric field carries the same mount of energy as the magnetic field. --> TRUE.

The energy carried by the electric field is:

$u_E = \frac{1}{2}\epsilon_0 E^2$

where $\epsilon_0$ is the vacuum permittivity.

The energy carried by the magnetic field is:

$u_B = \frac{1}{2\mu_0}B^2$

where $\mu_0$ is the vacuum permeability.

Given the following relationship:

$c=\frac{1}{\sqrt{\epsilon_0 \mu_0}}$

We can write

$E=cB=\frac{1}{\sqrt{\epsilon_0 \mu_0}}B$

$u_E = \frac{1}{2}\epsilon_0 (\frac{1}{\sqrt{\epsilon_0 \mu_0}}B)^2=\frac{1}{2\mu_0}B^2$

which means $u_E=u_B$ .

The electric field carries more energy than the magnetic field. --> FALSE, because in disagreement with the calculations above.

The frequency of the magnetic field is the same as the frequency of the electric field. --> TRUE. In an electromagnetic waves, electric field and magnetic field oscillate at the same frequency.

The frequency of the electric field is higher than the frequency of the magnetic field. --> FALSE, because in disagreement with the previous statement.

8 0

3 years ago

Three adjacent keys on a piano (F, F-sharp, and G) are struck simultaneously, producing frequencies of 349, 370, and 392 Hz. Wha

PSYCHO15rus [73]

Answer:

21 Hz, 43 Hz and 22 Hz

Explanation:

The computation of the beat frequencies that are generated by this discordant combination is as follows:

As we know that

beat frequencies = |f_1 - f_2|

For the first one

= |349 Hz - 370 Hz|

= 21 Hz

For the second one

= |349 Hz - 392 Hz|

= 43 Hz

And, for the third one

= |370 Hz - 392 Hz|

= 22 Hz

5 0

3 years ago

Hiro does not see a puddle of liquid on the lab table and accidentally touches the liquid. What should Hiro do next?

lys-0071 [83]

Answer: Option (B) is the correct answer.

Explanation:

It is advised that while conducting an experiment in a laboratory, always perform it under the supervision of your teacher.

When Hiro accidentally touches the liquid then he should immediately tell his teacher about it so that timely precaution can be taken to avoid any damage or side effect. Also, Hiro should rinse his hand in the sink because it will neutralize or decrease the effect of spilled liquid on his skin.

Thus, we can conclude that he should tell his teacher about the spill and rinse his hand in the sink.

6 0

3 years ago

Read 2 more answers

A ball is thrown vertically downward from the top of a 37.4-m-tall building. The ball passes the top of a window that is 15.4 m

Effectus [21]

Answer:

v= 20.8 m/s

Explanation:

Assuming no other forces acting on the ball, from the instant that is thrown vertically downward, it's only accelerated by gravity, in this same direction, with a constant value of -9.8 m/s2 (assuming the ground level as the zero reference level and the upward direction as positive).
In order to find the final speed 2.00 s after being thrown, we can apply the definition of acceleration, rearranging terms, as follows:

$v_{f} = v_{o} + a*t = v_{o} + g*t (1)$

We have the value of t, but since the ball was thrown, this means that it had an initial non-zero velocity v₀.
Due to we know the value of the vertical displacement also, we can use the following kinematic equation in order to find the initial velocity v₀:

$\Delta y = v_{o} *t + \frac{1}{2} * a* t^{2} (2)$

where Δy = yf - y₀ = 15.4 m - 37.4 m = -22 m (3)

Replacing by the values of Δy, a and t, we can solve for v₀ as follows:

$v_{o} = \frac{(\Delta y- \frac{1}{2} *a*t^{2})}{t} = \frac{-22m+19.6m}{2.00s} = -1.2 m/s (4)$

Replacing (4) , and the values of g and t in (1) we can find the value that we are looking for, vf:

$v_{f} = v_{o} + g*t = -1.2 m/s - (9.8m/s2*2.00s) = -20.8 m/s (5)$

Therefore, the speed of the ball (the magnitude of the velocity) as it passes the top of the window is 20.8 m/s.

4 0

3 years ago