Why would you be able to hear a sound traveling through a solid before you heard it through the air?

The percent efficiency of a machine can never be 100% (or greater), because in the real world some energy is always converted into a. heat b. work c. input force d. output force

The current in a hair dryer measures 11 amps. the resistance of the hair dryer is 12 ohms. what is the voltage?unit:

Which of these questions might a character ask if the conflict is man versus self? a. which path should i take to better myself? b. which boulder will be too heavy for me to carry? c. which friend is going to ditch me today? d. all of the above