An elevator without a ceiling is ascending with a constant speed of 10 m/s. A boy on the elevator shoots a ball directly upward, from a height of 2.0 m above the elevator floor. At this time the elevator floor is 28 m above the ground. The initial speed of the ball with respect to the elevator is 20 m/s. (Take g=9.8 m/s2 )
a. What maximum height above the ground does the ball reach?
b. How long does the ball take to return to the elevator floor?