Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_20820 ( "Gun" text, "m/v ft/s" real, "Shell (lb)" text, "Time to ft (m) at 25\u00b0 (seconds)" text, "Time to ft (m) at 40\u00b0 (seconds)" text, "Time to ft (m) at 55\u00b0 (seconds)" text, "Max. height (ft)" real )

### Question ###
How many feet per second does a shell move where the height range is 23500?

### Accurate SQL ###

SELECT MIN("m/v ft/s") FROM table_20820 WHERE "Max. height (ft)" = '23500'