Physics

The acceleration due to gravity near the Earth's surface is approximately 32 feet per second squared, meaning the velocity of a falling object increases by about 32 feet per second every second.

The speed of sound in dry air at 20 °C is approximately 343 m/s, which is a well-established standard value in physics and everyday science.

Albert Einstein formulated the mass-energy equivalence principle, expressed by the equation E=mc², which states that matter can be converted into energy.

Isaac Newton formulated the three laws of motion, which describe the relationship between a body and the forces acting upon it, laying the foundation for classical mechanics.

Flint glass is commonly used in making lenses and prisms because of its high refractive index and low dispersion, which improves optical performance. Other types like Pyrex and Jena glass are used for different purposes, and soft glass is not typically used for optical lenses or prisms.

A spring stores energy when it is compressed or stretched, which is called elastic potential energy. This energy is released when the spring returns to its original shape.

A neutron is a fundamental particle found in the nucleus of an atom and has no electric charge. Electrons have a negative charge and are outside the nucleus, while protons have a positive charge and are also in the nucleus.

Enrico Fermi is credited with creating the first nuclear reactor, which was a critical step in the development of nuclear energy and atomic research. The other options are inventions by different scientists.

Sound requires a medium to travel and cannot propagate through a vacuum because there are no particles to transmit the vibrations. Therefore, statement A is true, while sound can travel through solids like glass and liquids like water.

Acoustics is the branch of science that studies sound, its production, transmission, and effects, including sound waves. The other options relate to different fields: Aeronautics (study of flight), Aerostatics (study of gases at rest), and Aetiology (study of causes, especially of diseases).