Answer:
The correct answer is B
Explanation:
Let's calculate the electric field using Gauss's law, which states that the electric field flow is equal to the charge faced by the dielectric permittivity
Φ
= ∫ E. dA =
/ ε₀
For this case we create a Gaussian surface that is a sphere. We can see that the two of the sphere and the field lines from the spherical shell grant in the direction whereby the scalar product is reduced to the ordinary product
∫ E dA =
/ ε₀
The area of a sphere is
A = 4π r²
E 4π r² =
/ ε₀
E = (1 /4πε₀
) q / r²
Having the solution of the problem let's analyze the points:
A ) r = 3R / 4 = 0.75 R.
In this case there is no charge inside the Gaussian surface therefore the electric field is zero
E = 0
B) r = 5R / 4 = 1.25R
In this case the entire charge is inside the Gaussian surface, the field is
E = (1 /4πε₀
) Q / (1.25R)²
E = (1 /4πε₀
) Q / R2 1 / 1.56²
E₀ = (1 /4π ε₀
) Q / R²
= Eo /1.56
²
= 0.41 Eo
C) r = 2R
All charge inside is inside the Gaussian surface
=(1 /4π ε₀
) Q 1/(2R)²
= (1 /4π ε₀
) q/R² 1/4
= Eo 1/4
= 0.25 Eo
D) False the field changes with distance
The correct answer is B
Explanation:
Relation between potential energy and charge is as follows.
U = qV
or, 
= 
=
J
or, = 
Therefore, we can conclude that change in the electrical potential energy
is
.
Answer:
moment of inertia is 2.72 kg m²
Explanation:
given data
mass m = 10kg
height h = 4.5 m
radius r = 0.5 m
speed v = 6.5 m/s
to find out
moment of inertia
solution
we apply here conservation of energy
that is
mgh = 1/2 ×mv² + 1/2 × Iω²
here I is moment of inertia we find and
we know ω = Velocity / radius = 6.5 / 0.5 = 13
and g = 9.8
so put here all these value
10 (9.8) 4.5 = 1/2 ×(10)(6.5)² + 1/2 × I(13)²
441 = 211.25 + 1/2 × I( 169 )
I = 2.72
so moment of inertia is 2.72 kg m²
Answer:
it is sooo easy u need to use magnetic panels on the rail and put the magnet on the train it works under the principal of magnetic