4. Mr. S set up an experiment to see how the mass of a ball affects the distance it rolls off a ramp. Identify the dependent
variable.
a) Distance traveled by the ball
b) Height of the ramp
c) Mass of the ball

Hydroelectricity provides about 7 percent of the electricity generated in the united states. (a) explain how a hydroelectric power plant converts energy stored in water into electricity. (b) identify two factors that determine the amount of electricity that can be generated by an individual hydroelectricity power plant. (c) describe the two main types of land-based hydroelectric power plants. (d) describe two economic advantages and two environmental disadvantages of hydroelectricity.