## Weightless

Weight of an object is the gravitational force exerted on the object by the Earth’s gravitational field. An object is only truely weightless when there is no gravitational force acting on it. (Only true when object is infinitely far away from other masses where no gravitational field acts on it) An object is considered to be apparently weightless when it …

## Gravitational Field Lines

Gravitational field lines are always pointing towards the center of mass. Magnitude of gravitational field is proportional to the number of field lines per unit area through a surface perpendicular to the lines. Therefore, g is larger when lines are close together and smaller when they are far apart. Gravitational field strength close to the Earth can be considered as …

## Gravitational field strength

Gravitational field strength at a point is defined as the gravitational force per unit mass acting on a mass placed at that point. $$g = \frac{F}{m}$$ $$g = G \frac{M}{r^{2}}$$ Units of g is $N \, kg^{-1}$ or $m \, s^{-2}$. It is independent of test mass.

## Newton’s Law Of Universal Gravitation

Newton’s Law Of Universal Gravitation states that every particle in the Universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them. $F = G \frac{m_{1}m_{2}}{r^{2}}$ , where: F is magnitude of the gravitational force between the two point masses, G is …

## Gravitation

This topic covers “Gravitation” of A Level Physics. (Equivalent to Advanced Placement) Sub-Topic: Newton’s Law Of Universal Gravitation Gravitational Field Strength Gravitational Field Lines Weightless Gravitational Potential Energy Gravitational Potential Escape Speed Equations relating to U, g and F Questions: (With Worked Solutions) Set 1

## Thermal Physics

This topic covers “Thermal Physics” of A Level Physics. (Equivalent to Advanced Placement) If this is too advanced for you, you can try the more basic version here. Sub-topics: Internal Energy Thermal Contact Thermometers Thermodynamic Scale Specific heat capacity and Specific latent heat of fusion/vaporization Ideal Gas First Law Of Thermodynamics Melting and Boiling Questions: Set 1 Set 2 If you …

## Uncertainty

In general, uncertainty of a reading is determined to the nearest half of the smallest graduation. Always quoted to one significant figure.   Numerical value of uncertainty is the absolute uncertainty or actual uncertainty. Uncertainty of an instrument determined the number of decimal places that should be quoted for the readings taken from it. The number of decimal places I …