PHYS 241

Part C Keep the function x(t)=8∗t−2∗t∗tx(t)=8∗t−2∗t∗t in the Expression Evaluator. What is the value of the person's acceleration axax at t=2st=2s?

-4m/s^2

Part G Part complete How many times are the person's position, velocity, and acceleration equal to zero? Sort each item into the bin corresponding to the number of times it is equal to zero.

1. Acceleration, 2, Velocity 3. Position

Part H Part complete At approximately what times does the person change direction? Select all that apply.

2.0s and 6.0 s

Part I Part complete Which of the following statements is true about the acceleration during the entire course of this motion?

The acceleration increases linearly.

Part D Part complete In the previous question, the person had an initial velocity of 8m/s8m/s and a constant acceleration of −4m/s2−4m/s2. How would the maximum distance he travels to the right of the origin change if instead his initial velocity were doubled (vx,0=16m/svx,0=16m/s)?

The maximum distance would increase by a factor of four.

Part E Part complete Which of the following statements is true of the position at t=1.0st=1.0s?

The position is increasing at a rate decreasing in magnitude.

Part F Part complete Which of the following statements is true of the velocity at t=1.0st=1.0s?

The velocity is positive and the person is slowing down.

Part A Part complete First, you will focus on the relationship between velocity and position. Recall that velocity is the rate of change of position. This means that the velocity is equal to the slope of the Position vs. Time graph. Move the person to the position x=−6mx=−6m or enter -6.00 in the position box. If you dragged the person to position, click the Pause button and then the Clear button. Next, drag the person to the right to roughly x=6mx=6m and reverse his direction, returning him to the original position, at x=−6mx=−6m. Move the person relatively quickly, about a few seconds for the round trip. Your plots should look something like those shown below.

ZERO

Part B Part complete Similarly, acceleration is the rate of change of the velocity, so it is the slope of the Velocity vs. Time graph. Because it is difficult to drag the person in a consistent and reproducible way, use the Expression Evaluator under the Special Features menu for this question. Click Reset All and type in the function x(t)=8∗t−2∗t∗tx(t)=8∗t−2∗t∗t in the Expression Evaluator. Click the Play button and let the simulation run roughly 5 simulation seconds before pressing the Pause button. Use the zoom buttons to adjust the plots so they fit in the screen. You should see a plot similar to what you got in the previous question, but much smoother. Look at the Position vs. Time, Velocity vs. Time, and Acceleration vs. Time plots.

the velocity is zero but the acceleration is negative.