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stira [4]
2 years ago
11

How many neutrons does potassium have?

Physics
2 answers:
Sloan [31]2 years ago
6 0

Answer:

the answer is 20 neutrons

Explanation:

oksano4ka [1.4K]2 years ago
3 0

Answer:

20 neutrons

The nucleus of an atom of potassium contains 19 protons and 20 neutrons.

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A pendulum is made by letting a 4 kg mass swing at the end of a string that has a length of 1.5 meter. The maximum angle that th
olga nikolaevna [1]

Answer:

Approximately 7.8\; \rm J.

Explanation:

The change in the gravitational potential energy of the pendulum is directly related to the change in its height.

Refer to the sketch attached. The pendulum is initially at \rm P_2. Its highest point is at P_1. The length of segment \rm BP_2 gives the change in its height.

The lengths of \rm AP_1 and \rm AP_2 are simply the length of the string, 1.5\; \rm m. To find the length of \rm BP_2, start by calculating the length of \rm AB.

\rm AB forms a leg in the right triangle \rm \triangle AP_1B. Besides, it is adjacent to the 30^\circ angle \rm P_1\hat{A}B. Its length would be:

\rm AB = 1.5 \times \cos(30^\circ) \approx 1.30\; \rm m.

The length of \rm BP_2 would thus be

\rm BP_2 = AP_2 - AB = 1.5 - 1.30 \approx 0.20\; \rm m.

The change in gravitational potential energy can be found with the equation

\Delta \mathrm{GPE} = m \cdot g \cdot \Delta h. In this equation,

  • m is the mass of the object,
  • g \approx 9.81\; \rm N \cdot kg^{-1} near the surface of the earth, and
  • \Delta h is the change in the object's height.

In this case, m = 4\; \rm kg and \Delta h \approx 0.20\; \rm m. Therefore:

\Delta \mathrm{GPE} = 4 \times 9.81 \times 0.20 \approx 7.8\; \rm J.

6 0
3 years ago
A parachute falling to the ground.<br><br>​
butalik [34]

Answer:

a parachute falling to the ground is uniform

7 0
2 years ago
An object is dropped from rest from the top of a 400 m cliff on Earth. If air resistance is negligible, what is the distance the
IrinaVladis [17]

Answer:

176.58 m

Explanation:

t = Time taken = 6 seconds

u = Initial velocity = 0

v = Final velocity

s = Displacement

g = Acceleration due to gravity = 9.81 m/s² = a

Equation of motion

s=ut+\dfrac{1}{2}at^2\\\Rightarrow s=0\times t+\dfrac{1}{2}\times 9.81\times 6^2\\\Rightarrow s=176.58\ m

The object travels 176.58 m from the cliff in 6 seconds.

8 0
3 years ago
A thermometer is removed from a room where the temperature is 70° F and is taken outside, where the air temperature is 10° F. Af
vekshin1

Answer:

T=51.64^\circ F

t=180.10s

Explanation:

The Newton's law in this case is:

T(t)=T_m+Ce^{kt}

Here, T_m is the air temperture, C and k are constants.

We have

70^\circ F in t=0

So:

T(0)=70^\circ F\\T(0)=10^\circ F+Ce^{k(0)}\\70^\circ F=10^\circ F+C\\C=70^\circ F-10^\circ F=60^\circ F

And we have 60^\circ F in t=30 s, So:

T(30)=60^\circ F\\T(30)=10^\circ F+(60^\circ F)e^{k(30)}\\60^\circ F=10^\circ F+(60^\circ F)e^{k(30)}\\50^\circ F=(60^\circ F)e^{k(30)}\\e^{k(30)}=\frac{50^\circ F}{60^\circ F}\\(30)k=ln(\frac{50}{60})\\k=\frac{ln(\frac{50}{60})}{30}=-0.0061

Now, we have:

T=10^\circ F+(60^\circ F)e^{-0.0061t}(1)

Applying (1) for t=1 min=60s:

T=10^\circ F+(60^\circ F)e^{-0.0061*60}\\T=10^\circ F+(60^\circ F)0.694\\T=10^\circ F+41.64^\circ F\\T=51.64^\circ F

Applying (1) for T=30^\circ F:

30^\circ F=10^\circ F+(60^\circ F)e^{-0.0061t}\\30^\circ F-10^\circ F=(60^\circ F)e^{-0.0061t}\\-0.0061t=ln(\frac{20}{60})\\t=\frac{ln(\frac{20}{60})}{-0.0061}=180.10s

8 0
3 years ago
Sonar signals and infrared light are are used to send messages to submarines deep under water. If we compare the two signals, wh
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