Donna has observed that her father can control the speed of their grandfather clock by adjusting the height of the weight on the end of the pendulum. donna thinks that the pendulum will move faster when the weight is lowered, and wants to test her idea. donna gets a stopwatch and measures the time it takes for the pendulum to swing twenty times when the weight is moved to its lowest position. donna begins to move the pendulum up by 1 cm and continues to measure the time for twenty swings of the pendulum. donna records her data.

the  frequency of a wave represents  the number of wavelengths that pass a specific point per second. the unit for  frequency  is hertz (hz).

happy to

pls mark as brainliest

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."

sulfur dioxide

explanation: acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. these substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.