ripple

Some have images, but the ones that don't are as follows: Sound waves moves down a hall past an open doorway. Waves of which wavelength would have the hardest time diffracting through the doorway into the room? A. 5 centimeters B. 2 meters C. 100 meters D. All of the above would easily...

...outward at a speed of 60 cm/s.? Find the rate at which the area within the circle is increasing. a) after 2 secs b) after 5 secs c) after 7 secs

...at a speed of 60 cm/s. ...? Find the rate at which the area within the circle is increasing (a) after 1s, after 5s? Does this problem make sense to anyone? Can anyone explain it to me por favor? :]