A subwoofer is a type of speaker which plays only the very low notes in a song or movie. Which of the following
frequencies would you expect to be able to hear from a subwoofer?

10 Hz

25 Hz

750 Hz

1,050 Hz

Modify the equation fδt=δ (mv) to find the force of friction.

During takeoff, the sound intensity level of a jet engine is 170db at a distance of 34 m. what's the sound intensity level at a distance of 1.0 km?

The focal length of a relaxed human eye is approximately 1.7 cm. when we focus our eyes on a close up object, we can change the refractive power of the eye by about 16 diopters. (a) does the refractive power of our eyes increase or decrease by 16 diopters when we focus closely? explain. (b) calculate the focal length of the eye when we focus closely.