Hello I would like help with question 71 through 76 thank you.

76. You reach out a second-story window that is 5 m above the sidewalk and throw a 0.1-kg ball straight upward with 6 J of kinetic energy. a. What is the ball's gravitational potential energy when it is released? b. What is the ball's gravitational potential energy just before hitting the sidewalk? 5 m c. What is the ball's kinetic energy just before hitting the sidewalk? d. How would the answer to part (c) change if the ball had initially been thrown straight down with 6 ] of kinetic energy? 77. What average power does a weight lifter need to lift 300 lb a distance of 4 ft in 0.8 s? 78. If an 80-kg sprinter can accelerate from a standing start to a speed of 10 m/s in 3 s, what average power is 71. A 145-g baseball is thrown straight upward with kinetic generated? energy 8.7 J. When the ball has risen 6 m, find (a) the 79. If a CD player uses electricity at a rate of 15 W, how much work done by gravity, (b) the ball's kinetic energy, and energy does it use during an 8-h day? (c) the ball's speed. 80. If a hair dryer is rated at 1500 W, how much energy does 72. What is the gravitational potential energy of a ball with it require in 5 min? a weight of 50 N when it is sitting on a shelf 1.5 m above