The formular for determinatio of mass number is this:
Mass number = number of proton + number of neutron
From the question, we are told that:
Mass number = 39
Proton number = 19
Number of proton = ?
Number of neutron = mass number - number of proton
Number of neutron= 39 - 19 = 20
Therefore, number of neurtron = 20.
Answer:
Explanation:
We know that the electric force equation is:

- k is the electric constant

- r is the distance between the particles
- q1 and q2 are the particle
Now, we have three particles, the first one at x=0, the second one at x=2a and the third in some place between these two particle.
1. Let's find the electric force between the first particle and the third particle.



r(31) is the distance between 3 and 1
2. Now, let's find the electric force between the third particle and the second particle.



r(32) is the distance between 3 and 2.
Now,
or 
The net force must be zero so:
![F_{31}+F_{32}=0[\tex][tex]k\frac{2q^{2}}{r_{31}^{2}}-k\frac{q^{2}}{r_{32}^{2}}=0[\tex] [tex]kq^{2}(\frac{2}{r_{31}^{2}}-\frac{1}{r_{32}^{2}})=0[\tex] [tex]kq^{2}(\frac{2}{r_{31}^{2}}-\frac{1}{(2a-r_{31})^{2}})=0[\tex] It means that:[tex]\frac{2}{r_{31}^{2}}-\frac{1}{(2a-r_{31})^{2}}](https://tex.z-dn.net/?f=F_%7B31%7D%2BF_%7B32%7D%3D0%5B%5Ctex%5D%3C%2Fp%3E%3Cp%3E%5Btex%5Dk%5Cfrac%7B2q%5E%7B2%7D%7D%7Br_%7B31%7D%5E%7B2%7D%7D-k%5Cfrac%7Bq%5E%7B2%7D%7D%7Br_%7B32%7D%5E%7B2%7D%7D%3D0%5B%5Ctex%5D%20%20%20%3C%2Fp%3E%3Cp%3E%5Btex%5Dkq%5E%7B2%7D%28%5Cfrac%7B2%7D%7Br_%7B31%7D%5E%7B2%7D%7D-%5Cfrac%7B1%7D%7Br_%7B32%7D%5E%7B2%7D%7D%29%3D0%5B%5Ctex%5D%20%3C%2Fp%3E%3Cp%3E%5Btex%5Dkq%5E%7B2%7D%28%5Cfrac%7B2%7D%7Br_%7B31%7D%5E%7B2%7D%7D-%5Cfrac%7B1%7D%7B%282a-r_%7B31%7D%29%5E%7B2%7D%7D%29%3D0%5B%5Ctex%5D%20%3C%2Fp%3E%3Cp%3EIt%20means%20that%3A%3C%2Fp%3E%3Cp%3E%5Btex%5D%5Cfrac%7B2%7D%7Br_%7B31%7D%5E%7B2%7D%7D-%5Cfrac%7B1%7D%7B%282a-r_%7B31%7D%29%5E%7B2%7D%7D)
We just need to solve it for r(31)


Therefore the distance from the origin will be:
I hope it helps you!
Answer:
Frequency = 5.49Hz
Explanation:
Given the following data
Velocity = 41m/s
Wavelength = 225m
Making frequency the subject of formula, we have;
Substituting into the equation, we have;
Frequency = 5.49Hz
Therefore, the frequency of the earthquake is 5.49 Hertz.
The plane's heading is 4.61 degrees south of east, which is the direction the pilot needs to steer the plane in order to reach her objective and the trip takes 1.83 hours.
<h3>What is the distance?</h3><h3 />
Distance is a numerical representation of the distance between two objects or locations.
The distance can refer to a physical length or an estimate based on other factors in physics or common use. |AB| is a symbol for the distance between two points A and B.
Let the pilot's heading be theta south with an east direction. The resultant the velocity will be;

Hence the direction of the plane heading is 4.61 degrees south of east
b)
The resultant speed of the plane(V)is found as;

Hence, the trip takes 1.83 hours.
To learn more about the distance refer to the link;
brainly.com/question/26711747
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