Pls helppp Safia and Priya investigate friction. Here is the equipment they use. They pull the wooden block with a forcemeter. They repeat the investigation using different materials. (a) What two measurements should they make?​

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.