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Physics: explore STEM content (page 27 of 27) · openstem
Explore STEM Content
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Physics
Mechanics, electromagnetism and quantum on openstem — flashcards, notes, quizzes, plots and sketches shared by the community. Study free, or clone anything into your library.
A material that lets heat move through it easily, like metal. Heat conductors feel cold to the touch because they carry heat away from your warm hand quickly.
What fast means Speed is how quickly something covers ground. Fast means a lot of distance in a short time; slow means only a little in the same time. You compare speeds constantly without thinking. A car beats a bike, a bike beats walking.
What are the two classes of fundamental fermions in the Standard Model, and what distinguishes them?1 / 10
Quarks and leptons. Quarks carry color charge and participate in the strong interaction (in addition to the electroweak); leptons carry no color charge and interact only electroweakly. Both are spin-½ fermions.
What is the Coulomb barrier problem in stellar fusion, and how does quantum tunnelling resolve it?1 / 7
Classically, two positively charged nuclei need enough kinetic energy to overcome their mutual electrostatic repulsion before the short-range strong force can bind them — but typical thermal energies in stellar cores (~1 keV) are far below the MeV-scale Coulomb barrier. Quantum tunnelling allows a nonzero probability of fusion even when the classical kinetic energy is insufficient, with the tunnelling probability given by the Gamow factor — exponentially sensitive to energy, but nonzero even far below the barrier.
Run the relationship backwards So far, currents made magnetic fields. Induction goes the other way: a changing magnetic field creates a current in a nearby loop, with no battery anywhere. Lenz's law: it fights back That minus sign is a whol
AMotion that repeats itself over and over in a regular patternBMotion that only happens once and then stopsCMotion that always speeds up over timeDMotion that only occurs in outer space