The figure shows the speedometer readings as a car comes to a stop.Solve graphically for the acceleration at t = 7.0 s. A) 2.5 m/s² B) - 2.5 m/s² C) - 2.0 m/s² D) 2.0 m/s²

Question

Quizplus · Accepted Answer

To solve for acceleration graphically, we need to look at the slope of the velocity-time graph at t = 7.0 s. Since the car is coming to a stop, we know the acceleration will be negative (i.e. deceleration).

Looking at the graph, we see that the speedometer reading is decreasing from 27 m/s to 22 m/s between t = 6.0 s and t = 8.0 s. Drawing a straight line connecting these two points on the graph, we can find the slope of this line (which represents the average acceleration during this time period).

Using the slope formula (slope = rise/run), we get:

slope = (22 m/s - 27 m/s) / (8.0 s - 6.0 s) 
slope = -2.5 m/s^2

Since the slope is negative, we know that the acceleration is also negative (i.e. deceleration). Therefore, the correct answer is B) -2.5 m/s^2.

The Figure Shows the Speedometer Readings as a Car Comes