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  2. Dynamical friction - Wikipedia

    en.wikipedia.org/wiki/Dynamical_friction

    The effect of dynamical friction explains why the brightest (more massive) galaxy tends to be found near the center of a galaxy cluster. The effect of the two body collisions slows down the galaxy, and the drag effect is greater the larger the galaxy mass. When the galaxy loses kinetic energy, it moves towards the center of the cluster.

  3. Scientific research on the International Space Station

    en.wikipedia.org/wiki/Scientific_research_on_the...

    [1] [2] The 2005 NASA Authorization Act designated the American segment of the International Space Station as a national laboratory with the goal of increasing the use of the ISS by other federal agencies and the private sector. [3] Research on the ISS improves knowledge about the effects of long-term space exposure on the human body.

  4. Tidal force - Wikipedia

    en.wikipedia.org/wiki/Tidal_force

    Figure 1: Tidal interaction between the spiral galaxy NGC 169 and a smaller companion [1]. The tidal force or tide-generating force is the difference in gravitational attraction between different points in a gravitational field, causing bodies to be pulled unevenly and as a result are being stretched towards the attraction.

  5. Vacuum energy - Wikipedia

    en.wikipedia.org/wiki/Vacuum_energy

    A field in physics may be envisioned as if space were filled with interconnected vibrating balls and springs, and the strength of the field is like the displacement of a ball from its rest position. The theory requires "vibrations" in, or more accurately changes in the strength of, such a field to propagate as per the appropriate wave equation ...

  6. An Inquiry Concerning the Source of the Heat Which Is Excited ...

    en.wikipedia.org/wiki/An_Inquiry_Concerning_the...

    Rumford also argued that the seemingly indefinite generation of heat was incompatible with the caloric theory. He contended that the only thing communicated to the barrel was motion. Rumford made no attempt to further quantify the heat generated or to measure the mechanical equivalent of heat.

  7. Friction - Wikipedia

    en.wikipedia.org/wiki/Friction

    Fluid friction describes the friction between layers of a viscous fluid that are moving relative to each other. [7] [8] Lubricated friction is a case of fluid friction where a lubricant fluid separates two solid surfaces. [9] [10] [11] Skin friction is a component of drag, the force resisting the motion of a fluid across the surface of a body.

  8. Spacecraft flight dynamics - Wikipedia

    en.wikipedia.org/wiki/Spacecraft_flight_dynamics

    A space vehicle's flight is determined by application of Newton's second law of motion: =, where F is the vector sum of all forces exerted on the vehicle, m is its current mass, and a is the acceleration vector, the instantaneous rate of change of velocity (v), which in turn is the instantaneous rate of change of displacement.

  9. Quantum fluctuation - Wikipedia

    en.wikipedia.org/wiki/Quantum_fluctuation

    3D visualization of quantum fluctuations of the quantum chromodynamics (QCD) vacuum [1]. In quantum physics, a quantum fluctuation (also known as a vacuum state fluctuation or vacuum fluctuation) is the temporary random change in the amount of energy in a point in space, [2] as prescribed by Werner Heisenberg's uncertainty principle.