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In quantum field theory, the Casimir effect (or Casimir force) [1] is a physical force acting on the macroscopic boundaries of a confined space which arises from the quantum fluctuations of a field. The term Casimir pressure is sometimes used when it is described in units of force per unit area.
The net force exerted by the air occurs as a pressure difference over the airfoil's surfaces. [82] Pressure in a fluid is always positive in an absolute sense, [83] so that pressure must always be thought of as pushing, and never as pulling. The pressure thus pushes inward on the airfoil everywhere on both the upper and lower surfaces.
The force and torque vectors that arise in applying Newton's laws to a rigid body can be assembled into a screw called a wrench. A force has a point of application and a line of action, therefore it defines the Plücker coordinates of a line in space and has zero pitch. A torque, on the other hand, is a pure moment that is not bound to a line ...
Mass–energy equivalence states that all objects having mass, or massive objects, have a corresponding intrinsic energy, even when they are stationary.In the rest frame of an object, where by definition it is motionless and so has no momentum, the mass and energy are equal or they differ only by a constant factor, the speed of light squared (c 2).
In both cases the lift vector is the same (as seen by an observer on the ground), but in the latter the vertical axis of the aircraft points downwards, making the lift vector's sign negative. In turning flight the load factor is normally greater than +1. For example, in a turn with a 60° angle of bank the load factor is +2. Again, if the same ...
The phenomenon of static electricity requires a separation of positive and negative charges. When two materials are in contact, electrons may move from one material to the other, which leaves an excess of positive charge on one material, and an equal negative charge on the other. When the materials are separated, they retain this charge imbalance.
The bladder should be emptied before a person's blood pressure is measured since this can increase blood pressure by up to 15/10 mmHg. [91] Multiple blood pressure readings (at least two) spaced 1–2 minutes apart should be obtained to ensure accuracy. [92] Ambulatory blood pressure monitoring over 12 to 24 hours is the most accurate method to ...
The volume of body fluid, blood glucose, oxygen, and carbon dioxide levels are also tightly homeostatically maintained. The volume of extracellular fluid in a young adult male of 70 kg (154 lbs) is 20% of body weight – about fourteen liters. Eleven liters are interstitial fluid and the remaining three liters are plasma. [7]