Question

question 9
5 points
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an elevator is moving upward with a speed of 11 m/s. three seconds later, the elevator is still moving upward, but its speed has been reduced to 5.0 m/s. what is the average acceleration of the elevator during the 3.0 s interval?
5.3 m/s², upward
2.0 m/s², downward
5.3 m/s², downward
2.0 m/s², upward
2.7 m/s², downward

Explanation:

Step1: Identify initial and final velocities

Let the upward - direction be positive. Initial velocity $v_0 = 11\ m/s$, final velocity $v = 5.0\ m/s$, and time interval $\Delta t=3.0\ s$.

Step2: Use the acceleration formula

The formula for average acceleration is $a=\frac{v - v_0}{\Delta t}$. Substitute the values: $a=\frac{5 - 11}{3}=\frac{- 6}{3}=-2.0\ m/s^2$. The negative sign indicates the acceleration is in the downward direction.

Answer:

2.0 m/s², downward