In Mathematica, how to compute physical

Question

I want to calculate the speed of a car:

   180 km / 2 hour
    (*  25 m/s *)

this is a simple question, but I do not know how to implement

You can use CTRL + = to enter your units free form. See the last bullet in the Details section here — Greg Hurst, Dec 02 '16 at 03:08
Please search "unit" in the document. 还有，来把这个读了：http://note.youdao.com/share/?id=abd51087f44c0b6a41ff6022d549dc41&type=note#/ — xzczd, Dec 02 '16 at 05:13

score 12 · Accepted Answer · answered Dec 02 '16 at 05:09

A few things that gave me trouble at first were (1) the units are always strings; they are capitalized and they are plural. For example

{Quantity[180, "Kilometers"], 
Quantity[2,"Hours"],
Quantity[6,"Feet"]}

(2) When PhysicalConstants are entered, they are not plural. For example,

Quantity[5,"ElectronCharge"]
UnitConvert[%,"SIBase"]

(3) To find out how to enter a quantity, use the Ctrl= key and the InputForm function. For example:

Ctrl= 1 amp   //InputForm
Ctrl= -10 V   //InputForm
Ctrl= 21.1kΩ  //InputForm
Ctrl= 0.53 Å  //InputForm

Please see the documentation. Also, searching this forum for previous questions about Quantity and UnitConvert is highly recommended.

Note that while most units are plural, there are several exceptions. For example: "UkraineSovietRuble" and "AstronomicalUnit". An absence of pluralization is most commonly seen with currency units. — theorist, Mar 27 '17 at 01:53

In **Mathematica**, how to compute physical