Global Challenges OCR Physics A

Speed

Speed

The rate at which an object covers distance, calculated as distance traveled divided by time taken, typically measured in units like meters per second (m/s) or kilometers per hour (km/h).

Acceleration

The rate of change of velocity of an object with respect to time, a vector quantity calculated as (final velocity - initial velocity) / time taken.

Human Reaction Time

The delay between observation and action in humans, around 0.25 seconds, influencing driving and distance traveled during reaction time.

Fossil Fuels

Derived from decomposed organic matter, non-renewable due to long formation timescales, used for generating thermal energy through combustion.

Nuclear Fuels

Uranium and plutonium sources releasing energy through nuclear fission, with concerns about safety and waste disposal.

Biofuels

Derived from organic materials, renewable and carbon-neutral, used for electricity generation.

Red Shift

Phenomenon where light from an object moving away from an observer shifts towards longer wavelengths, indicating the expansion of the universe.

Big Bang

Cosmological model suggesting the universe expanded from a high-density state, evolving over billions of years, supported by evidence like Red Shift and CMBR.

Life Cycle of Star

Process starting from dust and gas clouds, leading to star formation, fusion of hydrogen to form helium, and eventual collapse into a white dwarf or supernova.

Radiation Emission

Process of releasing energy in the form of waves or particles from a source, such as radioactive materials or electromagnetic sources.