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physics-f2-notes
... Hard magnetic materials are those materials that are not easily magnetised but retain their magnetism for long after magnetisation e.g. steel. They are used in making permanent magnets. Storing magnets A bar magnet tends to become weaker with time due to self-demagnetisation. This is caused by the p ...
... Hard magnetic materials are those materials that are not easily magnetised but retain their magnetism for long after magnetisation e.g. steel. They are used in making permanent magnets. Storing magnets A bar magnet tends to become weaker with time due to self-demagnetisation. This is caused by the p ...
Vector Addition
... A vector quantity can be represented graphically by a straight line with an arrowhead at its end. The direction in which the arrow points gives the sense of the vector and the length of the line indicates the vector’s magnitude. For example, a force of 3 N acting horizontally might be described by a ...
... A vector quantity can be represented graphically by a straight line with an arrowhead at its end. The direction in which the arrow points gives the sense of the vector and the length of the line indicates the vector’s magnitude. For example, a force of 3 N acting horizontally might be described by a ...
Forces between charges Forces on charges
... (c) Suppose a charge Q exerts a force F on a test charge q that is brought near to it. By how much would the force exerted by Q increase if the test charge increased by a factor of a, where a can be any constant (i.e. a = 17 or 5 or 7.812, etc.)? By how much would the ratio of the force on the test ...
... (c) Suppose a charge Q exerts a force F on a test charge q that is brought near to it. By how much would the force exerted by Q increase if the test charge increased by a factor of a, where a can be any constant (i.e. a = 17 or 5 or 7.812, etc.)? By how much would the ratio of the force on the test ...
Weightlessness
![](https://commons.wikimedia.org/wiki/Special:FilePath/Foale_ZeroG.jpg?width=300)
Weightlessness, or an absence of 'weight', is an absence of stress and strain resulting from externally applied mechanical contact-forces, typically normal forces from floors, seats, beds, scales, and the like. Counterintuitively, a uniform gravitational field does not by itself cause stress or strain, and a body in free fall in such an environment experiences no g-force acceleration and feels weightless. This is also termed ""zero-g"" where the term is more correctly understood as meaning ""zero g-force.""When bodies are acted upon by non-gravitational forces, as in a centrifuge, a rotating space station, or within a space ship with rockets firing, a sensation of weight is produced, as the contact forces from the moving structure act to overcome the body's inertia. In such cases, a sensation of weight, in the sense of a state of stress can occur, even if the gravitational field was zero. In such cases, g-forces are felt, and bodies are not weightless.When the gravitational field is non-uniform, a body in free fall suffers tidal effects and is not stress-free. Near a black hole, such tidal effects can be very strong. In the case of the Earth, the effects are minor, especially on objects of relatively small dimension (such as the human body or a spacecraft) and the overall sensation of weightlessness in these cases is preserved. This condition is known as microgravity and it prevails in orbiting spacecraft.