Final answer:
The hypothesis that decreasing the size of solid metal would alter its density is false because density is an intrinsic property of a material. Other related physics concepts involve kinetic and potential energy changes during the flight of a rock, the induction of electric current when dropping a magnet through a copper tube, and the fact that wave-particle duality applies only at the quantum level.
Step-by-step explanation:
The hypothesis that if the size of a solid metal were decreased, its density would also increase in the same way is false. Density is defined as mass per unit volume. When the size of a solid is decreased without changing its mass, its volume shrinks, but the mass remains the same, causing no change in density. Density is an intrinsic property, meaning it doesn't change with the size of the sample.
Looking at other related concepts, the statement that if a rock is thrown into the air, the increase in the height would increase the rock's kinetic energy, and then the increase in the velocity as it falls to the ground would increase its potential energy, is false. In fact, as the rock goes higher, its potential energy increases and kinetic energy decreases. When it falls back, kinetic energy increases as potential energy decreases.
When you drop a bar magnet through a copper tube, it does indeed induce an electric current in the tube, which is true. This is a result of Lenz's Law and Faraday's law of electromagnetic induction.
Wave-particle duality is false for objects on the macroscopic scale. It's a phenomenon that is observed at the quantum level, for particles such as photons and electrons.
Lastly, for why a sound travels faster through a solid material than through the air, the explanation is because solid materials are denser than air. This allows sound waves, which are vibrations of the particles of a medium, to transfer energy more efficiently through the dense arrangement of atoms in solids.