How Does Gravity Cause Tides?
An object in orbit cannot change its orbit unless it gains or loses orbital energy. This means that the orbital energy must be constant unless energy is transferred to another object. An object is always in free fall when orbiting another object. In particular, the Moon is always falling towards the Earth. The Moon wants to obey Newton’s first law which states that an object in motion remains in motion along a straight line. However, The gravity of Earth pulls the Moon towards Earth. This creates an elliptical orbit.
Earth pulls harder on the feet than on the head as the feet are closer to the center of the Earth than the head is. However, It is not noticeable as the difference is very small. On the scale of planets, the effect of pulling stronger on nearer objects is quite noticeable. The Moon pulls on the near side of Earth harder than it does in the middle. This creates one tidal bulge. So, Water piles up on the tidal bulge towards the Moon. The Moon also pulls the center of Earth harder than it does on the backside of Earth. This creates a second tidal bulge. So, We end up with two tidal bulges. This means that the tides stay fixed and we move into and out of the tides.