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  2. List of unsolved problems in chemistry - Wikipedia

    en.wikipedia.org/wiki/List_of_unsolved_problems...

    RNA folding problem: Is it possible to accurately predict the secondary, tertiary and quaternary structure of a polyribonucleic acid sequence based on its sequence and environment? Protein design : Is it possible to design highly active enzymes de novo for any desired reaction?

  3. Specific impulse - Wikipedia

    en.wikipedia.org/wiki/Specific_impulse

    Specific impulse should not be confused with total thrust. Thrust is the force supplied by the engine and depends on the propellant mass flow through the engine. Specific impulse measures the thrust per propellant mass flow. Thrust and specific impulse are related by the design and propellants of the engine in question, but this relationship is ...

  4. Arrow pushing - Wikipedia

    en.wikipedia.org/wiki/Arrow_pushing

    Arrow pushing or electron pushing is a technique used to describe the progression of organic chemistry reaction mechanisms. [1] It was first developed by Sir Robert Robinson.In using arrow pushing, "curved arrows" or "curly arrows" are drawn on the structural formulae of reactants in a chemical equation to show the reaction mechanism.

  5. Impulse (physics) - Wikipedia

    en.wikipedia.org/wiki/Impulse_(physics)

    Impulse has the same units and dimensions (MLT −1) as momentum. In the International System of Units, these are kg⋅m/s = N⋅s. In English engineering units, they are slug⋅ft/s = lbf⋅s. The term "impulse" is also used to refer to a fast-acting force or impact.

  6. Angular momentum coupling - Wikipedia

    en.wikipedia.org/wiki/Angular_momentum_coupling

    An example of the first situation is an atom whose electrons only experience the Coulomb force of its atomic nucleus. If we ignore the electron–electron interaction (and other small interactions such as spin–orbit coupling), the orbital angular momentum l of each electron commutes with the total Hamiltonian. In this model the atomic ...

  7. Chemical oscillator - Wikipedia

    en.wikipedia.org/wiki/Chemical_oscillator

    In chemistry, a chemical oscillator is a complex mixture of reacting chemical compounds in which the concentration of one or more components exhibits periodic changes. They are a class of reactions that serve as an example of non-equilibrium thermodynamics with far-from-equilibrium behavior.

  8. Template:Specific impulse examples - Wikipedia

    en.wikipedia.org/wiki/Template:Specific_impulse...

    Specific impulse of various propulsion technologies Engine Effective exhaust velocity (m/s) Specific impulse (s) Exhaust specific energy (MJ/kg) Turbofan jet engine (actual V is ~300 m/s) 29,000 3,000 Approx. 0.05 Space Shuttle Solid Rocket Booster: 2,500 250 3 Liquid oxygen–liquid hydrogen: 4,400 450 9.7 NSTAR [1] electrostatic xenon ion ...

  9. Dirac delta function - Wikipedia

    en.wikipedia.org/wiki/Dirac_delta_function

    The impulse response can be computed to any desired degree of accuracy by choosing a suitable approximation for δ, and once it is known, it characterizes the system completely. See LTI system theory § Impulse response and convolution. The inverse Fourier transform of the tempered distribution f(ξ) = 1 is the delta function.