A balloonist floating at an altitude of 150m accidently drops his book and starts to ascend at a constant velocity of 1.2m/s. How will the balloon be when the book reaches the ground?
find v of the book at ground
(1/2) m v^2 = m g h
so
v = sqrt (2 g h)
= sqrt (9.81 *150/2)
= 27.1 m/s
average book speed down = 27.1/2 = 13.6 m/s
time book fell = 150/13.6 = 11 seconds
so
the balloon is at 150 + 1.2 * 11
= 163 meters