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12-14. A car is to be hoisted by elevator to the fourth
Chapter 12, Problem 12-14(choose chapter or problem)
12-14. A car is to be hoisted by elevator to the fourth floor of a parking garage, which is 48 ft above the ground. If the elevator can accelerate at 0.6 ft/s2, decelerate at 0.3ft/s2, and reach a maximum speed of 8 ft/s, determine the shortest time to make the lift, starting from rest and ending at rest.
Questions & Answers
QUESTION:
12-14. A car is to be hoisted by elevator to the fourth floor of a parking garage, which is 48 ft above the ground. If the elevator can accelerate at 0.6 ft/s2, decelerate at 0.3ft/s2, and reach a maximum speed of 8 ft/s, determine the shortest time to make the lift, starting from rest and ending at rest.
ANSWER:Step 1 of 5
For constant acceleration, we can utilize the three following equations:
(1)
… (2)
…(3)
Where is the final velocity, is the initial velocity, is the constant acceleration , is the time, and are the initial and final displacement of a particle, respectively. Where denotes the total distance travelled.
Step 2 of 5
Using equation (2), determine the maximum velocity of the elevator as it lifts up.