Light years are the distance light can travel in a full year. They are used because there are really big distances in the universe that are easier to measure with a really large form of measurement (light years).
Answer:
can you translate the question
into english
Answer:
It is a measure of the electric force per unit charge on a test charge.
Explanation:
The magnitude of the electric field is defined as the force per charge on the test charge.
Since we define electric field as the force per charge, it will have the units of force divided by the unit of charge. This implies that the SI unit of electric field is given as Newton/Coulomb (N/C).
Answer:
answer is option 4
Explanation:
you have to use option 4 because u need to find out initial velocity (Vi)
Answer:
proof in explanation
Explanation:
First, we will calculate the number of half-lives:
![n = \frac{t}{t_{1/2}}](https://tex.z-dn.net/?f=n%20%3D%20%5Cfrac%7Bt%7D%7Bt_%7B1%2F2%7D%7D)
where,
n = no. of half-lives = ?
t = total time passed = 2100 million years
= half-life = 700 million years
Therefore,
![n = \frac{2100\ million\ years}{700\ million\ years}\\\\n = 3](https://tex.z-dn.net/?f=n%20%3D%20%5Cfrac%7B2100%5C%20million%5C%20years%7D%7B700%5C%20million%5C%20years%7D%5C%5C%5C%5Cn%20%3D%203)
Now, we will calculate the number of uranium nuclei left (
):
![n_u = \frac{1}{2^{n} }(total\ nuclei)\\\\n_u = \frac{1}{2^{3} }(6400\ million)\\\\n_u = \frac{1}{8}(6400\ million)\\\\n_u = 800\ million](https://tex.z-dn.net/?f=n_u%20%3D%20%5Cfrac%7B1%7D%7B2%5E%7Bn%7D%20%7D%28total%5C%20nuclei%29%5C%5C%5C%5Cn_u%20%3D%20%5Cfrac%7B1%7D%7B2%5E%7B3%7D%20%7D%286400%5C%20million%29%5C%5C%5C%5Cn_u%20%3D%20%5Cfrac%7B1%7D%7B8%7D%286400%5C%20million%29%5C%5C%5C%5Cn_u%20%3D%20%20800%5C%20million)
and the rest of the uranium nuclei will become thorium nuclei (
)
![n_{th} = total\ nuclei - n_u\\n_{th} = 6400\ million-800\ million\\n_{th} = 5600\ million](https://tex.z-dn.net/?f=n_%7Bth%7D%20%3D%20total%5C%20nuclei%20-%20n_u%5C%5Cn_%7Bth%7D%20%3D%206400%5C%20million-800%5C%20million%5C%5Cn_%7Bth%7D%20%3D%205600%5C%20million)
dividing both:
![\frac{n_{th}}{n_u}=\frac{5600\ million}{800\ million} \\\\n_{th} = 7n_u](https://tex.z-dn.net/?f=%5Cfrac%7Bn_%7Bth%7D%7D%7Bn_u%7D%3D%5Cfrac%7B5600%5C%20million%7D%7B800%5C%20million%7D%20%5C%5C%5C%5Cn_%7Bth%7D%20%3D%207n_u)
<u>Hence, it is proven that after 2100 million years there are seven times more thorium nuclei than uranium nuclei in the rock.</u>