If two sounds are at slightly different frequencies, beats can be heard at a frequency equal to the difference in frequency of the two sources.

The graph shows a trend in an ecosystem over time caused by increased pollution in the region. what can you conclude from the graph? a. there’s lower biodiversity among birds. b. there’s a higher reproductive rate among birds. c. there’s a significant decline in the number of producers. d. other types of animals were unaffected by pollution.

In this food web, which group would increase in number if snakes were eliminated? a. producers b. decomposers c. primary consumers d. secondary consumers e. tertiary consumers

Which object has the least amount of kinetic energy? a. a car driving down a road b. a soccer ball rolling down a hill c. a bicycle locked to a bike rack d. a satellite orbiting earth