An elevator cage travels through a vertical shaft of length
PHYSICS · Multi-part · AP · Physics 1: Algebra-based · Force and Translational Dynamics · Force and Translational Dynamics
Problem
An elevator cage travels through a vertical shaft of length 120m. Starting from rest at the bottom, it accelerates uniformly upward for 4s, then continues at the constant speed attained, and finally comes to rest at the top by uniform deceleration for the last 4s. The total time taken for the entire journey is 16s. A passenger of mass 70kg stands on a spring balance on the floor of the cage throughout the ride.
(i) Using suitable kinematical relations, determine the magnitude of the uniform acceleration during the first 4s and the constant speed maintained during the middle portion of the trip.
(ii) Calculate the maximum and minimum readings recorded by the spring balance during the complete journey.
(iii) For what fraction of the total travel time does the passenger experience an apparent weight greater than the true weight? Show all steps clearly.