The net force must be zero
This is in accordance to Newton's first law, which states that any object in motion will remain in motion and any object at rest will remain at rest unless acted upon by an unbalanced force. An unbalanced force is one where the net force is not zero. If no unbalanced force is applied to a moving object, it will keep moving forever. The reason that we do not observe this in our daily lives is due to friction acting as the unbalanced force.
Answer:

Explanation:
As we know that magnetic field due to torroid is given as

this is approximately constant magnetic field along the axis of the torroid
now the flux linked with one coil of the torroid is given as


now total flux of N number of coils is given as

now we know that self inductance is the property of coil in which flux of the coil will link with the current in the coil
So we know that


Kepler's third law is used to determine the relationship between the orbital period of a planet and the radius of the planet.
The distance of the earth from the sun is
.
<h3>
What is Kepler's third law?</h3>
Kepler's Third Law states that the square of the orbital period of a planet is directly proportional to the cube of the radius of their orbits. It means that the period for a planet to orbit the Sun increases rapidly with the radius of its orbit.

Given that Mars’s orbital period T is 687 days, and Mars’s distance from the Sun R is 2.279 × 10^11 m.
By using Kepler's third law, this can be written as,


Substituting the values, we get the value of constant k for mars.


The value of constant k is the same for Earth as well, also we know that the orbital period for Earth is 365 days. So the R is calculated as given below.



Hence we can conclude that the distance of the earth from the sun is
.
To know more about Kepler's third law, follow the link given below.
brainly.com/question/7783290.
Answer:
t = 4.41 10⁻⁴ years
Explanation:
For this exercise we must use the concept of average life time, which is the time in which the quantity and substance decays in half
= ln2 / λ
Let's calculate the decay constant of plutonium
λ = ln2 /
λ = ln 2 / 2.44 10⁵
λ = 2.84 10⁻⁶ s⁻¹
Radioactive decay is a first order process
N = No e (-λ t)
Where N is the number of nuclei, the mass is this by molecular weight
m = N PM
m / PM = m₀ / PM e (- λ t)
m / m₀ = e (- λ t)
-λ t = ln (m / m₀)
t = -1 /λ ln (m/m₀)
t = - 1 / 2.84 10⁻⁶ ln (0.1 / 0.35)
t = 4.41 10⁻⁴ years
Answer:
y = 138.96 m
Explanation:
The angle subtended by the moon is the mean of the angle of the arc between the two most extreme points of the moon, we can see that the angle is very small, so we can approximate this arc to a straight line and then use the trigonometric relationships
sin θ = y / L
where L = 15.9 10³ m and θ = 8.74 10⁻³ rad
y = L sin θ
y = 15.9 10³ sin (8.74 10⁻³)
y = 15.9 10³ 0.0087399
y = 138.96 m