Question

question 9
choose the best answer from the options that follow each question.
which of the following situations represents a positive displacement of a carton? assume positive position is measured vertically upward along a y - axis.
the door closes and the elevator moves from the 10th to the 4th floors.
when the elevator doors open, the delivery person lifts the dolly over the threshold of the elevator.
the delivery person pushes the dolly to the back of the elevator while pressing a floor button.
a delivery person waiting for an elevator lowers a carton onto a dolly.
question 10
rank in decreasing order the distances traveled by objects having the following pairs of average velocity and time of motion.
i. (v_{avg}=+2.0 m/s), (t = 2.0 s)
ii. (v_{avg}=+3.0 m/s), (t = 2.0 s)
iii. (v_{avg}=-3.0 m/s), (t = 3.0 s)

Explanation:

Step1: Positive displacement upward

Upward movement along y-axis is positive. Lifting dolly upward (second option) is positive.

Step2: Distance = |v_avg * t|

I: |2.02.0|=4.0m; II: |3.02.0|=6.0m; III: |-3.0*3.0|=9.0m. Order: III>II>I.

Answer:

When the elevator doors open, the delivery person lifts the dolly over the threshold of the elevator.
III, II, I