Zach, whose mass is 80 kg, is in an elevator descending at 10 m/s. the elevator takes 3.0s to brake to a stop at the first floor.
a. what is zach's apparent weight before the elevator startsbraking ?
b. what is zach's apparent wight while the elevator is braking?

Two polarizers are oriented at 70∘∘ to one another. unpolarized light falls on them. what fraction of the light intensity is transmitted?

The mini-refrigerator fire was most likely caused by what type of wiring?

As you are trying to move a heavy box of mass m, you realize that it is too heavy for you to lift by yourself. there is no one around to , so you attach an ideal pulley to the box and a massless rope to the ceiling, which you wrap around the pulley. you pull up on the rope to lift the box. use g for the magnitude of the acceleration due to gravity and neglect friction forces. once you have pulled hard enough to start the box moving upward, what is the magnitude f of the upward force you must apply to the rope to start raising the box with constant velocity? express the magnitude of the force in terms of m, the mass of the box.