In the projection gravitation theory, there exists a merging model of black hole formation. Particles that meet the merging condition can be combined together to form a black hole. The essence of a black hole is an empty hole. A black hole is not a single object, it is a composite particles system. From this model, the black hole entropy formula can be easily derived out. This merging condition is equivalent to a temperature condition. From this black hole model, we can easily derive out the Verlinde¡¯s entropy gravity proposal formula and the Unruh formula. It is also proved that the Verlinde¡¯s entropy gravity proposal formula and the Unruh formula are actually equivalent. The Verlinde¡¯s entropy gravity proposal theory is not universally correct, but only in special circumstances. The gravitational acceleration produced by an object has a maximum value. Projection gravitation theory has important research value.

projection gravitation, black hole, empty hole, black hole entropy, black hole temperature, merging condition, temperature condition, the principle of uncertainty, Verlinde¡¯s entropy gravity proposal, Unruh formula, gravitational acceleration, quantum gravitation