Answer: (a) α = 
(b) For r≤R: B(r) = μ_0.
For r≥R: B(r) = μ_0.
Explanation:
(a) The current I enclosed in a straight wire with current density not constant is calculated by:

where:
dA is the cross section.
In this case, a circular cross section of radius R, so it translates as:




For these circunstances, α = 
(b) <u>Ampere's</u> <u>Law</u> to calculate magnetic field B is given by:
μ_0.
(i) First, first find
for r ≤ R:





Calculating B(r), using Ampere's Law:
μ_0.
.μ_0
B(r) =
.μ_0
B(r) =
.μ_0
For r ≤ R, magnetic field is B(r) =
.μ_0
(ii) For r ≥ R:

So, as calculated before:

I
Using Ampere:
B.2.π.r = μ_0.I
B(r) =
.μ_0
For r ≥ R, magnetic field is; B(r) =
.μ_0.
Answer:
The change in gravitational potential energy is -1.80x10⁵ J.
Explanation:
The change in gravitational potential energy is given by:


Where:
"i" is for final and "f" for final
m: is the mass
g: is the gravity = 9.81 m/s²
h: is the height
For the car and the passengers we have:
The minus sign is because when the elevator car and the passengers are up they have a bigger gravitational potential energy than when they are in the ground.
Therefore, the change in gravitational potential energy is -1.80x10⁵ J.
I hope it helps you!
Answer: The weight of a 72.0 kg astronaut on the Moon is 117.36 N.
Explanation:
Mass of the astronaut on the moon , m= 72 kg
Acceleration due to gravity on moon,g = 1.63 
According to Newton second law of motion: F = ma
This will changes to = Weight = mass × g

The weight of a 72.0 kg astronaut on the Moon is 117.36 N.
Answer:
3 in front means the no.of NH4 atoms
Hope it is correct ^_^