Find the potential energy associated with a 69-kg hiker atop new hampshire's mount washington, 1900 m above sea level. take the zero of potential energy at sea level.

An astronaut on the moon throws a baseball upward. the asatronaut is 6ft, 6in. tall, and the initial velocity of the ball is 30ft per second. the heigh s of the ball in feet is given by the equation s = -2.7^2 + 30t + 6.5, where t is the number of seconds after the ball was thrown. after how many seconds is the ball 16ft above the moon's surface?