Physical quantities

Physical quantities can be classified by:

1 ) The type of quantity in terms of magnitude and direction 2 ) in terms of the units used

Determine the base units of pressure

Pa= kg m^-1 s^-2

What could be a reason of having a numerically incorrect equation that is homogeneous

A missing constant number. The 1/2 in the kinetic equation does not effect the unit, but it is still incorrect.

A homogeneous equation

An equation that has the same units dimensions for both sides

Physical quantities that are divided interms of their unit are either

Base quantities and derived quantities

What are the conditions of accepting a physical equation

It must be numerically correct It must be homogenous

Name the seven base quantities and state their units

Length →m Time → s Mass → kg Current →A Temperature → K Amount of substance → mol Light intensity → c

Derived quantities

Quantities that are derived from other quantities and can be defined by word equations

Scaler

Quantities that are fully described by their magnitude

vector quantity

Quantity which is described by its magnitude and direction

Base quantities

Seven primary quantities which do not require other quantities to define them, they are considered to be the base that composes all other quantities in physics

What is meant by "an equation is homogeneous with respect to its units "?

That the equation, if expressed by its base units, is the same when compared to a different equation used to calculate the same quantity if expressed by its base units

The mole

The amount of a substance in grams, which has the same number of particles present in in 12 g of c-12

The ampere

The constant current which, if maintained in 2 straight parallel conductors of infinite length, and of negligible circular cross-section, and placed 1m apart in vacuum would produce a force enbetween the two wires equal to 0.0000002 newtons per unit meter of length ( two times ten to the power negative 7)

Second

The duration of 919 2631770 periods of the radiation corresponding to the transition between the 2 hyperfine levels of the ground state of ceasium- 133

Metre

The length travelled by an electromagnetic wave in vacuum in approximately 1/ 300000000 of a second in vacuum

The kilogram is...

The unit of mass; it is equal to the mass of the International prototype kilogram

The kelvin

The unit of the thermodynamic temperature, is the fraction of approximately 1/273 of the thermodynamic temperature of the triple point of water

Base units

Units for base quantities that are defined without reference to any other units

Derived units

Units for derived quantities that are defined with reference to the base quantities