A crane is used to lift air conditioning units to the top of a 5-story building. Each story is 3.5 m high. The crane accelerates the units while lifting the units past the first story and then lifts them at a constant velocity past the second through fourth stories. it hen slows to a stop by the top of the fifth story. if the rate of acceleration provided by the crane, both speeding up and slowing down, is 3 m/s^2, how long does it take an air conditioning unit to reach the top of the fifth story.

Question

A crane is used to lift air conditioning units to the top of a 5-story building. Each story is 3.5 m high. The crane accelerates the units while lifting the units past the first  story and then lifts them at a constant velocity past the second through fourth stories. it hen slows to a stop by the top of the fifth story. if the rate of acceleration provided by the crane, both speeding up and slowing down, is 3 m/s^2, how long does it take an air conditioning unit to reach the top of the fifth story.