Question

The gravitational potential energy of mass m at earths surface is mgr .Its gravitational potential at a height r from earths surface will be

Answer 1

When you quote a potential energy value, it is relative to the point where the potential energy is defined as zero. So, relative to earth’s surface, a mass has potenial energy mgh, so long as h is small relative to earth’s radius. For h=0, that potential is zero.