While completing an obstacle course, a runner moves 30 m north, 20 m south, then another 5 m north. At the end of the course, how far away is the runner from his starting point?

Most energy in an ecosystem comes originally from_

When a book falls from a shelf to the ground without anyone pushing on it, no work is done on the book. true or false

Which sentences describe point source pollution? in this type of pollution, the source of the pollution is single and easily identifiable. when runoff water from the melting of snow mixes with debris, it creates pollution. the runoff water, mixed with pollutants, reaches large areas with disastrous effects. alternatively, when a wastewater treatment plant releases harmful chemicals into a stream, the chemicals pollute the stream water because they are not treated for safety.