Which statement is true?
a. the speed of sound in air is inversely proportional to the temperature of the air.
b. the speed of sound in air is directly proportional to the temperature of the air.
c. the speed of sound in air is twice the temperature of the air.
d. the speed of sound in airis not affected by the temperature of the air.

Which of the following represents an upright image? a. -do b. +m c. -m d. +do

Name three different units of energy used to measure heat and describe what type of situations each is usually used.

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.