I read this sci-fi book some 30 years ago (but it was older than that by maybe ten years?).
The Earth collides with a planet, possibly from another universe. A piece of Earth is taken by it with the people on it. With limited resources they start exploring and discover a primitive and strange world with stuff like fast gelatinous masses which can dissolve entire human bodies. After killing one it becomes wood-like and they cut it with axes to discover only the ring of a previously "eaten" human.
The humans get old-Earth tech to work again (radio communications, planes...) and rebuild civilization on this new, alien planet.