Problem
The most destructive earthquake is Japan's history took place near Honshu in 2011. It was a magnitude 9 earthquake. Some of the aftershocks were magnitude 7.
How many times more energy was released by the magnitude 9 earthquake than by the magnitude 7 aftershocks?
How many times louder is a jackhammer than a washing machine if a jackhammer produces a 120 dB sound and a washing machine produces an 80 db sound?
According to an article on Fireworks and Hearing Loss, Any noise above 85 dB is considered unsafe. Most firecrackers produce sounds starting at 125 dB; Some Category 2 fireworks (sometimes called "garden fireworks") produce a sound intensity of 125 dB 0.5 meters away from the ignition site. Based on this information, what is the minimum distance friends and family should stand away from the ignition site to be at a safe hearing distance?