Zach, whose mass is 80 kg, is in an elevator descending at

10 m/s. The elevator takes 3.0 s to brake to a stopat the first

floor.

a. What is Zach's apparent weight before theelevator starts

braking?

b. What is Zach's apparent weight while theelevator is braking?

(a) apparent weight is actual weight = mg = (79) (9.81) = 775 N ANS (a) {reason: elevator is not accelerating therefore Z's net acceleration is "g"}

(b) elevator decelerates at 12/2.5 = - 4.80 m/s this reduces net acceleration acting on Z to (9.81 - 4.80) = 5.01 m/s² while braking with 5.01 m/s² acting on Z, his apparent weight = (79) (5.01) = 396 N ANS (b)