Solving 2.52 Elevator Problem how to calculate time of a complete trip?

AI Thread Summary
To solve the elevator problem, the elevator ascends 200 m with a maximum speed of 5 m/s and accelerates/decelerates at 1.0 m/s². It accelerates for the first 12.5 m, then travels at maximum speed for 175 m, and finally decelerates for the last 12.5 m. The total time for the complete trip can be calculated by determining the time for each of these three phases using kinematic equations. The initial calculation of 12.5 m for acceleration is correct and should be used to find the time for that phase. By summing the times for all phases, the total trip duration can be determined.
crystaldreams
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Homework Statement


Hi everyone, I am just wondering how you would solve this question..
2. Elevator Problem (Practice on Segmented Motion)
A hotel elevator ascends 200 m with maximum speed of 5 m/s. Its acceleration and
deceleration both have a magnitude of 1.0 m/s
How long does it take to make a complete trip from bottom to top.

Homework Equations


xf = xi + vi Δt + 1/2aΔt^2
v = vi + a*t

The Attempt at a Solution


There was another part to this question which asked me to solve for how far the elevator will move while accelerating to full speed from rest, and I got 12.5 m for that.
Do I plug in 12.5 m into this equation and solve for t? Thank you!
 
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Welcome to PF crystaldreams!

Assuming you did the first part right (EDIT: and you did), then the elevator will accelerate upward for the first 12.5 m, cruise at the max speed for 175 m, and then accelerate downward (meaning decelerate: i.e. reduce its upward speed) for the final 12.5 m, bringing it to a rest at the top. All you have to do is calculate the time required for each of these three phases of motion using the kinematics equations.
 
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