Sound that is perceptible by humans has frequencies from about 20 Hz to 20,000 Hz. In air at standard temperature and pressure, the corresponding wavelengths of sound waves range from 17 m to 17 mm. Sometimes speed and direction are combined as a velocity vector; wave number and direction are combined as a wave vector.
Price of a Stamp. The current price of a first class stamp is 47 cents. A domestic first class letter (1 oz.) is 47 cents. The price of each additional ounce is 21 cents. It will cost you 34 cents to send a domestic postcard.
USPS raises price of stamps. The U.S. Postal service is now charging Americans a penny more for stamps and postcard mailings. The price of a first-class stamp for domestic mail rose Sunday from 45 cents to 46 cents, while postcards cost 33 cents to send. The USPS rolled out the pricing changes alongside a new stamp â the Global Forever â which lets people mail one-ounce letters to anywhere in the world for $1.10. Other new services include free tracking for packages and the option of receiving a signature upon delivery for critical mail items, WALA reports.