# Search results

1. ### I Finding Real and Imaginary Parts of the complex wave number

The positive sign must be taken for k to be real. Taking the negative sign would result in a negative value and hence k would be imaginary since the square root of a negative number is imaginary.
2. ### B What is the evidence that there is gravitation?

That "something" we see, we simply label it as a force that we call gravity. This "thing" we call a force, with the name gravity, has certain properties and it explains a large amount of phenomenon that we see around us. Otherwise, we'll be going into an argument about semantics if I'm...
3. ### How does one exactly calculate gravity? How to portray a visual?

This isn't the equation for any two masses. This is for two spherical or point masses. The equation between a rod and a sphere would be different. You can get creative with different geometries. As others have said, you can plot the force as a function of separation distance.
4. ### What is the equal amount of force acting on both Earth and the Moon?

http://en.wikipedia.org/wiki/Newton%27s_law_of_universal_gravitation Just look up the values for the masses of the Earth and Moon and the separation of their centers of mass.