I am stuck on these 2 physics problems. Can anyone help? 1) A rock is dropped from a sea cliff and the sound of it striking the ocean is heard 2.5 s later. If the speed of sound is 340 m/s, how high is the cliff? 2) A first stone is dropped from the roof of a building. 2.30 s after that, a second stone is thrown straight down with an initial speed of 35.0 m/s, and it is observed that the two stones land at the same time. (a) How long did it take the first stone to reach the ground? (b) How high is the building? (c) What are the speeds of the two stones just before they hit the ground? Any help on how to get started would be great. Thanks in advance.