Would being born with a power level of 31 have helped Goku? Could anyone lift the Earth in the Frieza Saga?

[Speedster]

Yet both don't make any sense according to the laws of physics.

While someone generating energy out of nowhere, forming them into energy blasts and destroying a planet, a solar system or even the entire universe perfectly follows the laws of physics...

I'm tired of people saying this. It doesn't work like that - weight is determined by reference to the specific gravity field it's in. Something said to weigh 6 tons on Earth would weigh the same as something said to weigh 6 tons on the moon - their mass would just be different. If you took the 6 ton weight from Earth to the moon you'd have to then call it a 1 ton weight, and vice-versa.

The weight=mg is a simplification. Every object exerts a gravitational force according to Newton's law of universal gravitation. That is given by F=GMm/r^2. The Earth pulls you with a gravitational force (which you call weight) but you do pull the earth back with an equal and opposite force. The question of Goku “lifting the weight of the Earth” in a “literal sense” would therefore make sense in the context of say another Earth-like planet appearing say 2.2 metres above Earth’s surface and Goku standing in between the two planets with his arms stretched and preventing them from joining. Goku will have to counter the compressing forces to avoid getting squashed. That scenario would be equivalent of him lifting "half the earth’s weight" - that would be GM^2/(2*R^2) where M is the mass of the earth and R its radius. Of course, there are other issues with this whole thing, such as the ground giving up and effectively Goku getting buried, but here I would assume Goku using Ki to harden where he is standing or something.