You've always wondered about the acceleration of the elevators in the 101-story-tall Empire State Building. One day, while visiting New York, you take your bathroom scale into the elevator and stand on it. The scale reads 150 lbs as the door closes. The reading varies between 120 lbs and 170 lbs as the elevator travels 101 floors.
a.)What is the maximium acceleration upward?
b.)What is the maximium magnitude of the acceleration downward?
The Attempt at a Solution
First of all, i don't understand how the reading on the scale can vary under their weight if the elevator is going up. It seems to me that unless the acceleration is negative, their weight should be positive throughout going up. Where is my logic wrong?