Tina speaks using a nonelectric megaphone. The megaphone makes her voice louder in one direction. How does a megaphone work?
Select one:

It affects the vocal cords of a person and allows them to make louder sounds.

It increases the amplitude of spreading sound waves.

It changes the frequency of the spreading sound waves.

It collects sound waves and reflects them in a direction.

World class speed skaters can skate a 3,000-m course in about 4 minutes. what is their average speed for this course? a. 12.5 m/sb. 1.33 m/sc. 1.25 m/sd. 13.3 m/s

An atom that has gained or lost electrons is called an _

The starship enterprise is caught in a time warp and spock is forced to use the primitive techniques of the 20th century to determine the specific heat capacity of an unknown mineral. the 125-g sample was heated to 96.3°c and placed into a calorimeter containing 85.9 g of water at 20.0°c. the heat capacity of the calorimeter was 14.2 j/k. the final temperature in the calorimeter was 24.5°c. what is the specific heat capacity (in j/g°c) of the mineral? enter to 4 decimal places.