Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.

escape velocity is the initial speed that something would need to completely escape the gravity of a large body, like a star or a planet (such as the earth), by mere inertia.
escape velocity

the world conference of life and work was an ecumenic conference.
world conference of life and work

kazuma watanabe (渡邉 千真, watanabe kazuma, born) is a japanese football player.

kazuma watanabe