Many familiar physical quantities can be specified completely by giving a single number and the appropriate unit. For example, "a class period lasts ...

Vector multiplication of two vectors yields a vector product, with the magnitude equal to the product of the individual vectors multiplied by the sine of ...

To define some physical quantities, there is a need to specify both magnitude as well as direction. For example, when the U.S. Coast Guard dispatches a ...

A physical quantity is defined either by specifying its measurement method or by stating how it is calculated from other measurements. For example, ...

Scientists typically make repeated measurements of a quantity to ensure the quality of their findings and to evaluate both the precision and the accuracy ...

In any measurement, the precision of the measuring tool is an essential factor. An ordinary ruler, for example, can measure length to the closest ...

Scientists always try their best to record measurements with the utmost accuracy and precision. However, sometimes errors do occur. These errors can be ...

The position of an object defines its location relative to a convenient frame of reference at any particular time. A frame of reference is an arbitrary ...

To describe the motion of an object, one should first be able to describe its position (where it is at any particular time). More precisely, the position ...

Mass and weight are often used interchangeably in everyday conversation. For example,  medical records often show our weight in kilograms, but never ...

Newton's second law is closely related to his first law of motion. It mathematically gives the cause-and-effect relationship between force and changes ...

Tension is a force along the length of a medium, in particular, a force carried by a flexible medium, such as a rope or cable. The word "tension" ...

In the years before Newton, a general belief prevailed that different laws governed objects in the sky than objects on Earth. When Kepler wrote down the ...