Answer:
29.4 uN
Explanation:
The electric force between two charges can be calculated using Coulomb's Law. According to this law the force between two point charges is given as:

where k is a proportionality constant known as the Coulomb's law constant. Its value is
Nm²/C²
r = distance between charges = 70 cm = 0.7 m
q1 = q2 = 4nC =
C
The negative sign indicates that the charges are negative. In the formula we will only use the magnitude of the charges.
Using these values in the formula, we get:

Therefore, the magnitude of repulsive force between the given charges will be 29.4 uN
Answer:
Gamma Rays
Explanation:
Gamma rays have the highest energies the shortest wavelengths and the highest frequencies. They have the highest energies because they have the highest frequencies, the higher the frequency the more energy. ( I think, maybe double check with other answers )
Good Luck :)
It can be, but set also means many other things.
Answer:
Black Hole
Explanation:
A black hole is a very dense and massive stellar object, which has a field of gravity so large that not even light can escape it.
Since it does not emit light, <u>we cannot see them directly</u>, hence the name of black hole.
So in this case,<u> if the object has a mass of 8 solar masses that is enough to form a black hole</u>, and <u>also cannot be seen</u>, all of this indicates that the object we are talking about is a black hole.
It should be mentioned that although these objects do not emit light, because it cannot escape due to the immense force of gravity, black holes can be detected by a type of radiation emitted on their event horizon due to quantum effects called Hawking radiation .
Answer:
Explanation:
In order to solve this problem we need to make a free body diagram of the book and the forces that interact on it. In the picture below you can see the free body diagram with these forces.
The person holding the book is compressing it with his hands, thus exerting a couple of forces of equal magnitude and opposite direction with value F.
Now the key to solving this problem is to analyze the equilibrium condition (Newton's third law) on the x & y axes.
To find the weight of the book we simply multiply the mass of the book by gravity.
W = m*g
W = 1.3[kg] * 9.81[m/s^2]
W = 12.75 [N]