I- A sound is produced at one extremity of a metallic pipe of 1000 m of length. A person being at the other extremity discerns two sounds. (Vsound in the air is 340m/s) a- Explain this phenomenon.
b- The interval time between the two perceptions is equal to 2.5 s. Calculate the speed of sound in the metal.

According to the tide table below what time of day will the highest tide occur?

The empirical formula of a compound is ch2o and its mass is 120 amu/molecule, what is its formula?

Many bird species build nests in which they raise their offspring. one of these species is known as the magnolia warbler. breeding pairs of magnolia warblers build nests out of pieces of grass and twigs. the female warbler will then lay her eggs in the nest and sit on the eggs for a few weeks until they hatch. after the offspring have hatched, the female will continue to sit on the newborn chicks to keep them warm. both the male and the female bring food for the offspring to eat until the young are mature enough to find food on their own. which of these most likely describes why birds such as the magnolia warbler build nests in which to raise their offspring? a. nest building decreases the amount of energy used by the parent birds to raise their offspring to adulthood. b. nest building increases the probability that the offspring will survive and eventually produce offspring of their own. c. nest building decreases the amount of food that the offspring require the adult birds to provide. d. nest building increases the probability of the offspring being located by airborne predators.