The force that prevents ocean water from slipping into space is gravity. Gravity is the fundamental force of attraction between objects with mass, and it keeps everything on Earth, including the oceans, grounded.
Gravity pulls all objects towards the center of the Earth, creating a downward force. The Earth's mass and gravitational pull are substantial enough to keep the water in the oceans firmly in place. This gravitational force acts as a constant downward acceleration, counteracting any tendency for objects to move away from the Earth's surface.
The spherical shape of the Earth plays a significant role in distributing this gravitational force evenly across its surface. Gravity pulls the ocean water towards the center of the Earth, causing it to assume a roughly spherical shape itself, conforming to the Earth's curvature. This shape helps maintain equilibrium and prevents the water from simply falling off into space.
It's worth noting that the Earth's gravity extends far beyond its surface, creating an invisible gravitational field that extends into space. This gravitational field keeps the oceans and everything else on the planet bound to it.
So, the combination of the Earth's mass, gravitational pull, and the spherical shape of the planet work together to keep the oceans in place and prevent them from slipping into space.