The long term effects of mining include
a.
acid drainage
b.
erosion
c.
dust emissions
d.
all of the above

Forces that are equal in strength but opposite in direction are a.) balanced b.) unbalanced c.) always result in motion d.) do not exist

Flock x flock y flock z total pieces of food eaten (from previous page) 147 93 60 food percentage* % % % simulated number of birds in flock for 3rd generation** * divide each flock's total pieces of food by 300, the total number of pieces of food eaten. ** multiply the food percentage for each flock by the total number of birds (30).

Why are scientists concerned about the depletion of the ozone levels in the stratosphere?