A body of mass m moves along y such that at time t its position is y(t)= at^2 – bt + c, where a, b, c are constant. (a) Calculate the acceleration of the body. (b) What is the force acting on it? ​

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.