A hydroelectric power plant uses spinning turbines to transform the kinetic energy of moving water into electric energy with 74 % efficiency. That is, 74 %of the kinetic energy becomes electric energy. A small hydroelectric plant as the base of a dam generates 50 MW of electric power when the falling water has a speed of 18 m/s.

What is the water flow rate − kilograms of water per second − through the turbines?

Emmy kicks a soccer ball up at an angle of 45° over a level field. she watches the ball's trajectory and notices that it lands, two seconds after being kicked, about 20 m away to the north. assume that air resistance is negligible, and plot the horizontal and vertical components of the ball's velocity as a function of time. consider only the time that the ball is in the air, after being kicked but before landing. take "north" and "up" as the positive ‑ and ‑directions, respectively, and use ≈10 m/s2 for the downward acceleration due to gravity.