Answer: The rising and setting of the Sun.
The appearance and disappearance of the Moon.
Changes in season.
Appearance and disappearance of the Stars.
Explanation: The rising and setting of the Sun helps can be used as a standard to determine time since the rissing and setting of the Sun occurs at similar time and interval in a given geographical ocation.
The appearance and disappearance of the Moon which occurs during the night and early hours of the morning is similar in a given geographical locationation so it can be used as a standard for Time.
Change in season is another natural phenomenon which occurs at similar times in a given geographical location like Winter/summer, rainy/dry etc can be used as standards for time.
The appearance and disappearance of the Stars can also b used as standards for time in a given geographical location.
Answer:
E = k Q₁ / r²
Explanation:
For this exercise that asks us for the electric field between the sphere and the spherical shell, we can use Gauss's law
Ф = ∫ E .dA =
/ ε₀
where Ф the electric flow, qint is the charge inside the surface
To solve these problems we must create a Gaussian surface that takes advantage of the symmetry of the problem, in this almost our surface is a sphere of radius r, that this is the sphere of and the shell, bone
R <r <R_a
for this surface the electric field lines are radial and the radius of the sphere are also, therefore the two are parallel, which reduces the scalar product to the algebraic product.
E A = q_{int} /ε₀
The charge inside the surface is Q₁, since the other charge Q₂ is outside the Gaussian surface, therefore it does not contribute to the electric field
q_{int} = Q₁
The surface area is
A = 4π r²
we substitute
E 4π r² = Q₁ /ε₀
E = 1 / 4πε₀ Q₁ / r²
k = 1/4πε₀
E = k Q₁ / r²
The answer is Stay In Place
C) a substance that flows