-In the Bohr model, as it is known today, the electron is imagined to move in a circular orbit about a stationary proton. The fo
1 answer:
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Answer:
Thus the time taken is calculated as 387.69 years
Solution:
As per the question:
Half life of = 28.5 yrs
Now,
To calculate the time, t in which the 99.99% of the release in the reactor:
By using the formula:
where
N = No. of nuclei left after time t
= No. of nuclei initially started with
(Since, 100% - 99.99% = 0.01%)
Thus
Taking log on both the sides:
t = 387.69 yrs
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
Answer: 20.21 kg
Explanation:
The mass hanging from the pulley is pulling the cart. The force by which cart is being pulled is equal to weight of the hanging mass.
⇒F=0.200 kg ×9.8 m/s²=1.96 N
Since there is no other force acting on the cart and there is no friction, so this force will pull the cart.
The Cart covers 1.12 m distance in 4.8 s.
From the equation of motion,
s = u t + 0.5 × a t²
We will find the acceleration of the cart,
Distance covered, s = 1.12 m
Initial velocity, u = 0 ( staring from rest)
Time taken, t = 4.8 s
⇒1.12 m = 0 + 0.5 × a × (4.8 s)²
⇒a = 0.097 m/s²
Now the force which causes this acceleration is:
F = ma
where m is the mass of the cart and a is the acceleration of the cart
⇒1.96 N = m×0.097 m/s²
⇒m = 20.21 kg
Hence, the mass of the cart is 20.21 kg.