Final answer:
The statement about the penny returning to your hand because of shared velocity with the bus and the law of inertia is true. Newton's first law, the law of inertia, explains this behavior as there is no external horizontal force acting on the penny when tossed inside a moving bus with constant velocity.
Step-by-step explanation:
The statement that the reason a penny thrown straight up inside a bus will come back to your hand is that you, the bus, the air inside the bus, and the penny are moving at the same velocity is true. This concept is underpinned by Newton's first law of motion, often called the law of inertia. According to this law, an object in motion will stay in motion with constant velocity, and an object at rest will stay at rest, unless acted upon by a net external force. When you are inside a moving bus that is traveling at a constant velocity, and you throw a penny straight up, there is no net external force acting horizontally on the penny. The motion of the penny, bus, and yourself are all consistent in the horizontal direction due to inertia, ensuring the penny comes back to your hand if the velocity of the bus remains constant.