What causes tidal gravitational forces?

[shirin]

what is tidal gravitational force?

 

[zhermes]

Tidal forces are due to the difference in gravitational force on different parts/sides of an object.

Standing upright, on the surface of the earth, there is slightly strongly gravity acting on your feet, than on your head---the difference is so small that you would never notice it.

When you have two stars near each other, however, the effect can be significant. If stars (for example) are near enough, the gravitational force from the other star can be significantly stronger on one side, than on the other. This can lead to the star being torn apart. The effect is especially important near black-holes, and other high-mass & high-density objects. Even on such 'small' scales as the Earth and moon, tidal effects are clearly apparent, however, as they create the tides ~2 times a day.