Energy, Heat, Nuclear Physics and Related Concepts — Vocabulary Flashcards (Spring 2023)

A comprehensive set of vocabulary flashcards covering energy, heat, motion, thermodynamics, and nuclear physics concepts from the notes.

Energy

The capacity to do work or cause change; exists in multiple forms (kinetic, potential, thermal) and is conserved in isolated systems.

Calorie

A unit of energy used in nutrition; 1 Calorie (Cal) equals 1 kilocalorie (kcal), or 1000 calories.

Power

The rate at which energy is transferred or transformed; defined as energy divided by time (P = ΔE/Δt).

Kinetic energy

The energy of motion, given by (1/2) m v^2.

Heat

Thermal energy associated with the random motion of particles; not directed motion and reflects temperature.

Leidenfrost effect

Water droplets skim over a very hot surface because a vapor layer forms, insulating the liquid from the surface.

Heat engine

A device that converts heat into mechanical work; efficiency is always less than 100% due to energy losses.

Gravitational force

The attractive force between masses; proportional to the product of masses and inversely proportional to the square of the distance.

Weightlessness (orbit)

In orbit, objects experience apparent weightlessness because they are in continuous free fall around Earth, though gravity is still present.

Momentum

p = m v; the quantity of motion; conserved in the absence of external forces.

Air pressure (altitude)

Air pressure decreases with altitude; at high elevations it is much lower, making breathing harder.

Angular momentum

A measure of rotational motion; conserved in the absence of external torque.

Radioactivity

Decay of unstable atomic nuclei emitting radiation; not the same as an explosion.

Isotope

Atoms with the same number of protons (same element) but different numbers of neutrons.

Radiation dose sickness

Sickness symptoms arising from high radiation exposure; the threshold is around 100 rem depending on exposure.

Half-life

The time required for half of a radioactive substance to decay; after n half-lives, remaining amount is (1/2)^n.

Fission

Splitting of a heavy nucleus into lighter nuclei, releasing energy and neutrons.

Chain reaction

A sequence where one nuclear reaction triggers additional reactions to take place.

Enrichment

Increasing the proportion of fissile U-235 within uranium.

Fallout

Radioactive debris consisting of fission fragments produced by a nuclear explosion or accident.

Fusion (nuclear)

Joining light nuclei to form a heavier nucleus, releasing energy; fuel is abundant and can produce less long-lived waste than fission.

Fusion reactor advantage

Potential advantages include abundant fuel and reduced long-lived radioactive waste compared to fission.

Electric force vs gravity

Electromagnetic force is vastly stronger than gravity at subatomic scales and governs most atomic interactions.

Charge quantization

Fundamental particle charges come in discrete multiples of the elementary charge; charges are not arbitrary values.

Superconductors and levitation

Materials with zero resistance and expulsion of magnetic fields (Meissner effect); can enable levitation of magnets.

Earth’s magnetic field origin

Generated by electric currents in the Earth's outer core.

Transformers

Devices that transfer electrical energy between circuits via electromagnetic induction; operate with alternating current (AC).

Orbital velocity

The speed required to maintain a stable circular orbit around a planet, balancing inertia with gravity.

Thermal expansion

Materials expand when heated; gaps (like sidewalk joints) accommodate this expansion.

Electric generator

Device that converts mechanical energy into electrical energy by spinning a conductor in a magnetic field.