Question

hi

Answer 1

The moon's gravity attracts the water in the oceans causing a the water to swell into a "bump" on the side of the earth facing the moon. On the other side of the earth, the moons gravitational force is at a minimum, also causing a bump - away from the moon.
Because the sun is much further away than the moon, its gravitational force is less - about one quarter as much. This means that when the moon and sun are combined the force is 1.25 times the moon alone, and when not combined, about 0.75 times as much.

Answer 2

The moon has mass, therefore it has gravity. As the moon orbits the earth, its gravitational pull not only keeps the moon from departing its orbit due to centripetal force, it also pulls the ocean water around with it. A spring tide is when the Moon, Earth, and Sun fall in a straight line. These spring tides occur twice each month, during the full and new Moon, and we notice the greatest difference between high and low tide water levels. If the Moon is at perigee, the closest it approaches Earth in its orbit, the tides are especially high and low. When the Sun and Moon form a right angle, as when we see a half moon, their pulls fight each other and we notice a smaller difference between high and low tides. These are called neap tides. Factors such as the path the Moon takes around the Earth, our planet's tilt, the water's depth, and the geometry of the tidal basin affect tides. Therefore, not all coasts experience two high and two low tides each day.